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

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


int main(){
    
    cin >> n;
    cin >> x >> y;
    n--;
    
    for(int i = 1; i <= n; i++){
        cin >> a >> b;
        if(a!=x) s="NO";
        if(b!=y) s1="NO";
    }
    
    if(s1=="NO" && s=="NO") cout << "NO";
        else cout << "YES";
    
    return 0;
}