题解

#include <bits/stdc++.h>
using namespace std;

struct Activities{
    int start, end;
}a[1005];

bool cmp(Activities x, Activities y){
    return x.end < y.end;
}

int main(){
    int n; cin>>n;
    for(int i=0;i<n;i++) cin>>a[i].start>>a[i].end;
    sort(a, a+n, cmp);
    int lasts = a[0].end, cnt = 1;
    for(int i=0;i<n;i++){
        if(a[i].start >= lasts){
            lasts = a[i].end;
            cnt++;
        }
    }
    cout << cnt << endl;
    return 0;
}