Decrypt

input/code.cpp: In function 'int main()':
input/code.cpp:33:10: warning: array subscript has type 'char' [-Wchar-subscripts]
     asd[c][0] = x;
          ^
input/code.cpp:44:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       for (int j = 0; j < a.length(); j++) {
                                    ^
input/code.cpp:45:17: warning: array subscript has type 'char' [-Wchar-subscripts]
  a[j] = asd[a[j]][i];
                 ^
input/code.cpp:50:17: warning: array subscript has type 'char' [-Wchar-subscripts]
     r[s[i - 'a']].push_back(i);
                 ^
input/code.cpp:52:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < t.length(); i++) {
                                ^
input/code.cpp:53:10: warning: unused variable 'q' [-Wunused-variable]
     char q = t[i];
          ^

#include <bits/stdc++.h>
#define ll long long
#define N (1<<17)
#define ld long double
#define F first
#define S second
#define INF 1000111000
#define M 1000000007

using namespace std;

int asd[255][31];
vector<char> r[255];

bool dfs (int i, int k) {
  if (k == 0) return true;
  if (r[i].size() != 1) return false;
  return dfs(r[i][0], k - 1);
}

int main () {
  cin.sync_with_stdio(false);
  cin.tie(0);
  string s;
  cin>>s;
  int k;
  cin>>k;
  string t;
  cin>>t;
  int x = 'a';
  string a = "abcdefghijklmnopqrstuvwxyz";
  for (char c : s) {
    asd[c][0] = x;
    x++;
    //if (OOliOO[c] > 1) cout<<"impossible"<<endl, exit(0);
  }
  for (int i = 1; i < 31; i++) {
    for (int j = 'a'; j <= 'z'; j++) {
      asd[j][i] = asd[asd[j][i - 1]][i - 1];
    }
  }
  for (int i = 0; i < 31; i++) {
    if (k & (1<<i)) {
      for (int j = 0; j < a.length(); j++) {
	a[j] = asd[a[j]][i];
      }
    }
  }
  for (int i = 'a'; i <= 'z'; i++) {
    r[s[i - 'a']].push_back(i);
  }
  for (int i = 0; i < t.length(); i++) {
    char q = t[i];
    if (!dfs(t[i], min(k, 26))) cout<<"impossible"<<endl, exit(0);
    t[i] = a[t[i] - 'a'];
  }
  cout<<t<<endl;
}

/*
bcdefghijklmnopqrstuvwxyzz 27
bcdbaaaaaaaaaaaaaaaaaaaaaa 1
c
 * */

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED