CSES - BOI 2026 Mirror Day 2

Submission details
Task:	Sort
Sender:	FZiuzin
Submission time:	2026-04-17 12:25:52 +0300
Language:	C++ (C++20)
Status:	READY
Result:	6

Feedback
subtask	verdict	score
#1	ACCEPTED	6
#2	TIME LIMIT EXCEEDED	0
#3	TIME LIMIT EXCEEDED	0
#4	TIME LIMIT EXCEEDED	0
#5	TIME LIMIT EXCEEDED	0
#6	TIME LIMIT EXCEEDED	0
#7	TIME LIMIT EXCEEDED	0

Test results
test	verdict	time	subtask
#1	TIME LIMIT EXCEEDED	--	2, 6, 7	details
#2	ACCEPTED	0.00 s	1, 2, 3, 6, 7	details
#3	ACCEPTED	0.00 s	2, 6, 7	details
#4	ACCEPTED	0.00 s	1, 2, 3, 6, 7	details
#5	ACCEPTED	0.00 s	1, 2, 3, 6, 7	details
#6	ACCEPTED	0.00 s	1, 2, 3, 6, 7	details
#7	ACCEPTED	0.00 s	1, 2, 3, 6, 7	details
#8	ACCEPTED	0.00 s	1, 2, 3, 6, 7	details
#9	ACCEPTED	0.00 s	1, 2, 3, 6, 7	details
#10	ACCEPTED	0.00 s	1, 2, 3, 6, 7	details
#11	TIME LIMIT EXCEEDED	--	2, 6, 7	details
#12	TIME LIMIT EXCEEDED	--	2, 6, 7	details
#13	TIME LIMIT EXCEEDED	--	2, 6, 7	details
#14	TIME LIMIT EXCEEDED	--	2, 6, 7	details
#15	TIME LIMIT EXCEEDED	--	2, 6, 7	details
#16	TIME LIMIT EXCEEDED	--	3, 7	details
#17	TIME LIMIT EXCEEDED	--	3, 7	details
#18	TIME LIMIT EXCEEDED	--	3, 7	details
#19	TIME LIMIT EXCEEDED	--	3, 7	details
#20	TIME LIMIT EXCEEDED	--	3, 7	details
#21	TIME LIMIT EXCEEDED	--	3, 7	details
#22	TIME LIMIT EXCEEDED	--	3, 7	details
#23	TIME LIMIT EXCEEDED	--	3, 7	details
#24	TIME LIMIT EXCEEDED	--	4, 7	details
#25	TIME LIMIT EXCEEDED	--	4, 7	details
#26	TIME LIMIT EXCEEDED	--	4, 7	details
#27	TIME LIMIT EXCEEDED	--	4, 7	details
#28	TIME LIMIT EXCEEDED	--	4, 7	details
#29	TIME LIMIT EXCEEDED	--	4, 7	details
#30	TIME LIMIT EXCEEDED	--	5, 6, 7	details
#31	TIME LIMIT EXCEEDED	--	5, 6, 7	details
#32	TIME LIMIT EXCEEDED	--	5, 6, 7	details
#33	TIME LIMIT EXCEEDED	--	5, 6, 7	details
#34	ACCEPTED	0.14 s	5, 6, 7	details
#35	TIME LIMIT EXCEEDED	--	5, 6, 7	details
#36	TIME LIMIT EXCEEDED	--	6, 7	details
#37	TIME LIMIT EXCEEDED	--	6, 7	details
#38	TIME LIMIT EXCEEDED	--	6, 7	details
#39	TIME LIMIT EXCEEDED	--	6, 7	details
#40	TIME LIMIT EXCEEDED	--	6, 7	details
#41	TIME LIMIT EXCEEDED	--	6, 7	details
#42	TIME LIMIT EXCEEDED	--	7	details
#43	TIME LIMIT EXCEEDED	--	7	details
#44	TIME LIMIT EXCEEDED	--	7	details
#45	TIME LIMIT EXCEEDED	--	7	details
#46	TIME LIMIT EXCEEDED	--	7	details
#47	TIME LIMIT EXCEEDED	--	7	details
#48	TIME LIMIT EXCEEDED	--	7	details
#49	TIME LIMIT EXCEEDED	--	7	details
#50	TIME LIMIT EXCEEDED	--	7	details
#51	TIME LIMIT EXCEEDED	--	7	details
#52	ACCEPTED	0.00 s	1, 2, 3, 5, 6, 7	details
#53	ACCEPTED	0.00 s	1, 2, 3, 4, 5, 6, 7	details
#54	ACCEPTED	0.00 s	2, 5, 6, 7	details
#55	ACCEPTED	0.00 s	1, 2, 3, 4, 6, 7	details
#56	ACCEPTED	0.00 s	1, 2, 3, 6, 7	details
#57	TIME LIMIT EXCEEDED	--	6, 7	details
#58	ACCEPTED	0.20 s	3, 4, 7	details
#59	ACCEPTED	0.20 s	3, 7	details
#60	TIME LIMIT EXCEEDED	--	2, 6, 7	details
#61	TIME LIMIT EXCEEDED	--	2, 6, 7	details
#62	TIME LIMIT EXCEEDED	--	2, 6, 7	details
#63	TIME LIMIT EXCEEDED	--	2, 6, 7	details
#64	TIME LIMIT EXCEEDED	--	2, 6, 7	details

Code

#include <bits/stdc++.h>

using namespace std;
#define int int64_t

const int INF = 1e14;
const int MAXN = 2e5 + 5;

#define pb push_back
#define all(a) a.begin(), a.end()

int n,q;
int calc(vector<int> a, int l, int r)
{
    if (!is_sorted(a.begin() + l, a.begin() + r + 1))
    {
        return -1;
    }
    int res = 0;
    //cout << "left part sort" << is_sorted(a.begin(), a.begin() + l + 1) << '\n';
    if (!is_sorted(a.begin(), a.begin() + l + 1))
    {
        res++;
        sort(a.begin(), a.begin() + l + 1);
    }
    if (!is_sorted(a.begin() + r, a.end()))
    {
        res++;
        sort(a.begin() + r, a.end());
    }
    if (!is_sorted(all(a)))
    {
        return -1;
    }
    return res;
}
int solve(vector<int> a, int l, int r, bool turn)
{
    int inter = l + r - n;
    int point_r = 0, point_l = 0;
    for (int i = 0;i < l;i++)
    {
        if (a[i] > l)
        {
            point_r++;
        }
    }
    for (int i = r;i < n;i++)
    {
        if (a[i] < r)
        {
            point_l++;
        }
    }
    int res = 0;
    while (point_r > 0 || point_l > 0)
    {
        if (turn)
        {
            point_r -= inter;
        }
        else
        {
            point_l -= inter;
        }
        res++;
    }
    return res;
}
signed main()
{
    cin >> n >> q;
    vector<int> a(n);
    for (int i = 0;i < n;i++)
    {
        cin >> a[i];
        a[i]--;
    }
    while (q--)
    {
        int l, r;
        cin >> l >> r;
        l--;
        r = n - r;
        if (l < r)
        {
            cout << calc(a, l, r) << '\n';
        }
        else
        {
            vector<int> b = a;
            int resA = 0;
            if (!is_sorted(b.begin(), b.begin() + l + 1))
            {
                sort(b.begin(), b.begin() + l + 1);
                resA++;
            }

            if (!is_sorted(b.begin() + r, b.end()))
            {
                sort(b.begin() + r, b.end());
                resA++;
            }

            resA += solve(b, l, r, true);

            int resB = 0;
            b = a;

            if (!is_sorted(b.begin() + r, b.end()))
            {
                sort(b.begin() + r, b.end());
                resB++;
            }

            if (!is_sorted(b.begin(), b.begin() + l + 1))
            {
                sort(b.begin(), b.begin() + l + 1);
                resB++;
            }

            resB += solve(b, l, r, false);

            cout << min(resA, resB) << '\n';
        }
        
    }
    return 0;
}

Test details

Test 1

Subtask: 2, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`6 3 3 1 4 1 5 9 4 1 3 3 2 5` view save

correct output
`1 -1 2` view save

user output
(empty)

Test 2

Subtask: 1, 2, 3, 6, 7

Verdict: ACCEPTED

input
`2 1 548813503 548813503 1 1` view save

correct output
`0` view save

user output
`0` view save

Test 3

Subtask: 2, 6, 7

Verdict: ACCEPTED

input
`1 1 417021999 1 1` view save

correct output
`0` view save

user output
`0` view save

Test 4

Subtask: 1, 2, 3, 6, 7

Verdict: ACCEPTED

input
`10 10 20751947 20751947 20751947 494...` view save

correct output
`-1 -1 1 1 -1 ...` view save

user output
`-1 -1 1 1 -1 ...` view save

Test 5

Subtask: 1, 2, 3, 6, 7

Verdict: ACCEPTED

input
`10 10 12780811 19475241 19475241 683...` view save

correct output
`0 0 0 0 0 ...` view save

user output
`0 0 0 0 0 ...` view save

Test 6

Subtask: 1, 2, 3, 6, 7

Verdict: ACCEPTED

input
`10 10 14574963 14574963 14574963 864...` view save

correct output
`0 0 0 0 0 ...` view save

user output
`0 0 0 0 0 ...` view save

Test 7

Subtask: 1, 2, 3, 6, 7

Verdict: ACCEPTED

input
`10 10 237541216 237541216 35036522 6...` view save

correct output
`-1 -1 -1 2 -1 ...` view save

user output
`-1 -1 -1 2 -1 ...` view save

Test 8

Subtask: 1, 2, 3, 6, 7

Verdict: ACCEPTED

input
`10 10 319425549 513116712 539199939 ...` view save

correct output
`-1 -1 -1 -1 -1 ...` view save

user output
`-1 -1 -1 -1 -1 ...` view save

Test 9

Subtask: 1, 2, 3, 6, 7

Verdict: ACCEPTED

input
`10 10 54363219 54363219 110986323 11...` view save

correct output
`0 0 0 0 0 ...` view save

user output
`0 0 0 0 0 ...` view save

Test 10

Subtask: 1, 2, 3, 6, 7

Verdict: ACCEPTED

input
`10 5 55687086 550701455 326656159 5...` view save

correct output
`-1 -1 -1 -1 -1` view save

user output
`-1 -1 -1 -1 -1` view save

Test 11

Subtask: 2, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`10 10 35889584 588130796 815837475 8...` view save

correct output
`-1 -1 1 1 1 ...` view save

user output
(empty)

Test 12

Subtask: 2, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`10 10 679842175 48724877 720966351 6...` view save

correct output
`2 3 2 1 1 ...` view save

user output
(empty)

Test 13

Subtask: 2, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`10 10 893310183 811950921 338863962 ...` view save

correct output
`2 1 1 2 5 ...` view save

user output
(empty)

Test 14

Subtask: 2, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`10 10 221045363 282395847 441913686 ...` view save

correct output
`0 0 0 0 0 ...` view save

user output
(empty)

Test 15

Subtask: 2, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`10 10 509019662 983949268 960017302 ...` view save

correct output
`3 -1 3 3 3 ...` view save

user output
(empty)

Test 16

Subtask: 3, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 2277053 2277053 2277053 227705...` view save

correct output
`-1 -1 -1 -1 -1 ...` view save

user output
(empty)

Test 17

Subtask: 3, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 6767 16596 16596 27202 37272 4...` view save

correct output
`-1 -1 -1 -1 -1 ...` view save

user output
(empty)

Test 18

Subtask: 3, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 5393 5910 9099 15755 15755 164...` view save

correct output
`-1 -1 -1 -1 -1 ...` view save

user output
(empty)

Test 19

Subtask: 3, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 3779 4629 8999 10468 22605 227...` view save

correct output
`-1 1 2 -1 -1 ...` view save

user output
(empty)

Test 20

Subtask: 3, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 878 2791 10849 11861 13405 239...` view save

correct output
`-1 -1 -1 -1 -1 ...` view save

user output
(empty)

Test 21

Subtask: 3, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 430 1479 1992 2829 7152 14093 ...` view save

correct output
`-1 -1 -1 -1 -1 ...` view save

user output
(empty)

Test 22

Subtask: 3, 7

Verdict: TIME LIMIT EXCEEDED

input
`199997 200000 2733 10526 13882 14035 14689 3...` view save

correct output
`-1 -1 -1 -1 -1 ...` view save

user output
(empty)

Test 23

Subtask: 3, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 12345 13538 15407 18490 18984 ...` view save

correct output
`0 0 0 0 0 ...` view save

user output
(empty)

Test 24

Subtask: 4, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ...` view save

correct output
`-1 1 -1 -1 -1 ...` view save

user output
(empty)

Test 25

Subtask: 4, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ...` view save

correct output
`1 -1 1 -1 1 ...` view save

user output
(empty)

Test 26

Subtask: 4, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 2 2 1 1 2 1 2 1 2 2 2 1 1 1 2 ...` view save

correct output
`4 3 2 2 6 ...` view save

user output
(empty)

Test 27

Subtask: 4, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ...` view save

correct output
`0 0 0 0 0 ...` view save

user output
(empty)

Test 28

Subtask: 4, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 ...` view save

correct output
`8513 1099 35939 9299 19597 ...` view save

user output
(empty)

Test 29

Subtask: 4, 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 ...` view save

correct output
`178345 169257 62115 96143 64796 ...` view save

user output
(empty)

Test 30

Subtask: 5, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`5000 5000 1 2 3 4 5 6 7 8 9 10 11 12 13 ...` view save

correct output
`1 1 -1 1 -1 ...` view save

user output
(empty)

Test 31

Subtask: 5, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`5000 5000 1 2 3 4 5 6 7 8 9 72 145 47 19...` view save

correct output
`-1 2 -1 2 -1 ...` view save

user output
(empty)

Test 32

Subtask: 5, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`4999 5000 1 2 3 4 5 6 7 8 9 10 11 12 13 ...` view save

correct output
`-1 2 -1 -1 -1 ...` view save

user output
(empty)

Test 33

Subtask: 5, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`5000 5000 4033 4368 3086 3208 4313 388 8...` view save

correct output
`3 3 3 3 11 ...` view save

user output
(empty)

Test 34

Subtask: 5, 6, 7

Verdict: ACCEPTED

input
`5000 5000 1 2 3 4 5 6 7 8 9 10 11 12 13 ...` view save

correct output
`0 0 0 0 0 ...` view save

user output
`0 0 0 0 0 ...` view save

Test 35

Subtask: 5, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`5000 5000 5000 4999 4998 4997 4996 4995 ...` view save

correct output
`2039 1910 -1 687 673 ...` view save

user output
(empty)

Test 36

Subtask: 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`5000 5000 202010 457852 826471 926337 10...` view save

correct output
`-1 -1 2 -1 -1 ...` view save

user output
(empty)

Test 37

Subtask: 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`5000 5000 190583 326486 431922 462939 72...` view save

correct output
`-1 -1 -1 -1 2 ...` view save

user output
(empty)

Test 38

Subtask: 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`5000 5000 821998255 400550008 71790232 5...` view save

correct output
`5 3 3 2 5 ...` view save

user output
(empty)

Test 39

Subtask: 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`5000 5000 266174928 446601941 191252234 ...` view save

correct output
`3 3 414 4 3 ...` view save

user output
(empty)

Test 40

Subtask: 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`5000 5000 11621 243915 243915 949123 137...` view save

correct output
`0 0 0 0 0 ...` view save

user output
(empty)

Test 41

Subtask: 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`5000 5000 999767052 998555066 997822810 ...` view save

correct output
`919 459 505 833 809 ...` view save

user output
(empty)

Test 42

Subtask: 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 478025 478025 478025 478025 47...` view save

correct output
`-1 -1 2 2 2 ...` view save

user output
(empty)

Test 43

Subtask: 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 1810 2088 3022 3097 7459 7943 ...` view save

correct output
`2 -1 -1 2 -1 ...` view save

user output
(empty)

Test 44

Subtask: 7

Verdict: TIME LIMIT EXCEEDED

input
`199531 200000 11328 26391 30353 37063 44412 ...` view save

correct output
`-1 2 -1 2 2 ...` view save

user output
(empty)

Test 45

Subtask: 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 106738201 369187074 412614650 ...` view save

correct output
`2 12 3 19 3 ...` view save

user output
(empty)

Test 46

Subtask: 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 670611290 43427363 8475380 309...` view save

correct output
`3 5 3 3 3 ...` view save

user output
(empty)

Test 47

Subtask: 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 907542569 504758282 948727805 ...` view save

correct output
`3 33 3 3 3 ...` view save

user output
(empty)

Test 48

Subtask: 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 487056731 460461648 142698485 ...` view save

correct output
`3 3 3 3 3 ...` view save

user output
(empty)

Test 49

Subtask: 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 12772 23236 23236 23236 41149 ...` view save

correct output
`0 0 0 0 0 ...` view save

user output
(empty)

Test 50

Subtask: 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 999993539 999993361 999993361 ...` view save

correct output
`125375 16687 -1 84781 46147 ...` view save

user output
(empty)

Test 51

Subtask: 7

Verdict: TIME LIMIT EXCEEDED

input
`200000 200000 999993539 999993361 999993361 ...` view save

correct output
`94788 177608 95881 56377 179957 ...` view save

user output
(empty)

Test 52

Subtask: 1, 2, 3, 5, 6, 7

Verdict: ACCEPTED

input
`5 1 2 1 3 5 4 2 2` view save

correct output
`2` view save

user output
`2` view save

Test 53

Subtask: 1, 2, 3, 4, 5, 6, 7

Verdict: ACCEPTED

input
`2 1 1 2 1 1` view save

correct output
`0` view save

user output
`0` view save

Test 54

Subtask: 2, 5, 6, 7

Verdict: ACCEPTED

input
`4 1 2 1 4 3 3 2` view save

correct output
`2` view save

user output
`2` view save

Test 55

Subtask: 1, 2, 3, 4, 6, 7

Verdict: ACCEPTED

input
`10 10 1 1 1 1 2 2 1 1 2 2 7 1 2 6 4 5 ...` view save

correct output
`-1 1 -1 -1 -1 ...` view save

user output
`-1 1 -1 -1 -1 ...` view save

Test 56

Subtask: 1, 2, 3, 6, 7

Verdict: ACCEPTED

input
`10 10 181777772 181777772 181777772 ...` view save

correct output
`-1 -1 -1 -1 -1 ...` view save

user output
`-1 -1 -1 -1 -1 ...` view save

Test 57

Subtask: 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`100 10 92800811 524548163 939127795 9...` view save

correct output
`-1 -1 3 -1 3 ...` view save

user output
(empty)

Test 58

Subtask: 3, 4, 7

Verdict: ACCEPTED

input
`100 100000 2 2 2 1 2 2 2 2 1 2 1 1 1 2 2 ...` view save

correct output
`-1 -1 -1 -1 -1 ...` view save

user output
`-1 -1 -1 -1 -1 ...` view save

Test 59

Subtask: 3, 7

Verdict: ACCEPTED

input
`100 100000 172695325 172695325 172695325 ...` view save

correct output
`-1 -1 -1 -1 -1 ...` view save

user output
`-1 -1 -1 -1 -1 ...` view save

Test 60

Subtask: 2, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`4 10 869194539 239439572 968540665 ...` view save

correct output
`-1 2 -1 -1 -1 ...` view save

user output
(empty)

Test 61

Subtask: 2, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`10 10 55366041 112170735 112170735 5...` view save

correct output
`-1 -1 2 1 1 ...` view save

user output
(empty)

Test 62

Subtask: 2, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`10 10 156018639 156018639 445832758 ...` view save

correct output
`-1 1 -1 -1 2 ...` view save

user output
(empty)

Test 63

Subtask: 2, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`10 10 702507512 702507512 892090406 ...` view save

correct output
`-1 2 -1 2 2 ...` view save

user output
(empty)

Test 64

Subtask: 2, 6, 7

Verdict: TIME LIMIT EXCEEDED

input
`10 10 720324490 720324490 720324490 ...` view save

correct output
`-1 2 2 1 -1 ...` view save

user output
(empty)

BOI 2026 Mirror Day 2

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Test details

Test 1

Test 2

Test 3

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Test 5

Test 6

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Test 8

Test 9

Test 10

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Test 14

Test 15

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Test 18

Test 19

Test 20

Test 21

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Test 24

Test 25

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Test 28

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Test 30

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Test 33

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Test 35

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Test 40

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Test 49

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Test 63

Test 64

Tasks

Submissions (FZiuzin)