AC

#include <bits/stdc++.h>
using namespace std;
struct qujian {
    int l, r;
};
bool cmp(qujian x, qujian y) {
    if (x.l != y.l) return x.l < y.l;
    return x.r < y.r;
}
qujian a[50005];
int main() {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> a[i].l >> a[i].r;
    }
    sort(a, a + n, cmp);
    int L = a[0].l;
    int R = a[0].r;

    for (int i = 1; i < n; i++) {
        if (a[i].l <= R + 1) {
            if (a[i].r > R) {
                R = a[i].r;
            }
        } else {
            cout << "no" << endl;
            return 0;
        }
    }
    cout << L << " " << R << endl;
    return 0;
}

必须AC 不AC我是傻B