10763.cpp

#include <bits/stdc++.h>
using namespace std;
int arr[500001], ab[500001];
int compare(const void* a, const void* b) {
    int* ia = (int*)a;
    int* ib = (int*)b;
    return (*ia - *ib);
}

int main() {
    int i, j, n;
    while (scanf("%d", &n)) {
        if (n == 0) {
            break;
        }
        for (i = 0; i < n; i++) {
            scanf("%d %d", &arr[i], &ab[i]);
        }
        qsort(arr, n, sizeof(int), compare);
        qsort(ab, n, sizeof(int), compare);
        for (i = 0; i < n; i++) {
            if (arr[i] != ab[i]) {
                break;
            }
        }
        if (i == n) {
            printf("YES\n");
        } else {
            printf("NO\n");
        }
    }
    return 0;
}