#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define mk make_pair
#define pi pair<int, int>
#define fi first
#define se second
using namespace std;
map < int , int > m, m1;
int main() {
	int n;
	cin >> n;
	int x[n], y[n];
	for(int i = 0; i < n; i++) {
		cin >> x[i] >> y[i];
		m[x[i]]++;
		m1[y[i]]++;
	}
	int ch = 0;
	for(auto it : m) {
		if(it.se == n) {
			ch = 1;
			break;
		}
	}
	for(auto it : m1){
		if(it.se == n) {
			ch = 1;
			break;
		}
	}
	if(ch) {
		cout << "YES";
	} else {
		cout << "NO";
	}
	return 0;
}