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

#define MAX 100002

int main() {
	int i, n, x, y, a, b, flag1 = 0, flag2 = 0;
	cin>>n;
	cin>>x>>y;
	while (--n) {
	    cin>>a>>b;
	    if (a != x) flag1 = 1;
	    if (b != y) flag2 = 1;
	}
	if (flag1 == 0 || flag2 == 0) cout<<"YES"<<endl;
	else cout<<"NO"<<endl;
	return 0;
}