#include <bits/stdc++.h>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
int n,a,b,i;
set<int>sa,sb;
int main() {
    
    cin>>n;
    
    for(i=0;i<n;i++){
        cin>>a>>b;
        sa.insert(a);
        sb.insert(b);
    }
    
    if(sa.size()==1 || sb.size()==1) cout<<"YES"; else cout<<"NO";
    return 0;
}