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input/code.cpp: In function 'void Test()':
input/code.cpp:16:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |     freopen("temp\\in.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
input/code.cpp: In function 'int main()':
input/code.cpp:22:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
input/code.cpp:27:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         scanf("%d%d", &a, &b);
      |         ~~~~~^~~~~~~~~~~~~~~~

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>
typedef long long LL;
typedef std::pair<int, int> poi;

using std::make_pair;

const int N=200005;

poi p[N];

void Test()
{
    freopen("temp\\in.txt", "r", stdin);
}
int main()
{
    // Test();
    int n;
    scanf("%d", &n);

    for(int i=1; i<=n; i++)
    {
        int a, b;
        scanf("%d%d", &a, &b);
        p[i]=make_pair(a, b);
    }

    sort(p+1, p+n+1);

    int now = 0, ans = 0;
    for(int i=1; i<=n; i++)
    {
        int u = p[i].first, v = p[i].second;
        if(now <= u)
        {
            ans++;
            now = v;
        } else {
            if(v < now)
                now = v;
        }
    }

    printf("%d", ans);

    return 0;
}

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