#include <bits/stdc++.h>

using namespace std;

int x, y, n, a, b, k;
string s="YES", s1="YES";

int main(){
    cin >> n;
    cin >> x >> y;
    k=n/2;
    for(int i = 2; i <= n; i++){
        cin >> a >> b;
        if(a!=x) s="NO";
        if(b!=y) s1="NO";
    }
    
    if(s=="NO" && s1=="NO") cout << "NO";
        else cout << "YES";
    
    return 0;
}