#include <bits/stdc++.h>
#define loop1(i,n) for(int i = 0;i < n;i++)
#define loop2(i,n) for(int i = 1;i <= n;i++)
int mod(int x){return x < 0 ? -x:x;};
using namespace std;
int main(){
	ios::sync_with_stdio(0);
	int n,x,y; cin >> n;
	bool p = 0,q = 0,r = 0;
	loop1(i,n){
		int a,b; cin >> a >> b;
		if(i == 0){
			x = a; y = b;
		}
		else if(i == 1){
			if(x == a){
				p = 1;
			}
			else if(y == b) q = 1;
			else{
				r = 1;
			}
		}
		else{
			if(p && a != x) {
				r = 1;
			}
			else if(q && b != y) r = 1;
		}
	}
	if(r) cout << "NO" << endl;
	else cout << "YES" << endl;
}