문제
풀이
#include <iostream>
#include <vector>
using namespace std;
bool solve(void) {
int m, n; cin >> m >> n;
vector<bool> v(m, false);
while (n--) {
int l, r; cin >> l >> r; l--; r--;
for (int j=l; j<=r; j++) v[j] = true;
}
for (int i=0; i<m; i++) {
if (!v[i]) return false;
}
return true;
}
int main(void) {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout << (solve() ? "YES" : "NO");
return 0;
}