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


int main(){
    int n;
    cin >> n;
    int x0;
    int y0;
    cin >> x0 >> y0;
    int x1;
        int y1;
        cin >> x1 >> y1;
    bool no = false;
    if( x0 == x1){
        int x;
        int y;
        for(int a0 = 2; a0 < n; a0++){
        
        cin >> x >> y;
        
            if( x != x0 ){
                no = true; break;
                
            }
        }
        
    }
        
    else if( y0 == y1){
        
         int x;
        int y;
        for(int a0 = 2; a0 < n; a0++){
        
        cin >> x >> y;
        
            if( y != y0 ){
                no = true; break;
                
            }
        }
        
    }else{
        cout<<"NO\n";
}

    if(no)
        cout<<"NO\n";
      else
        cout<<"YES\n";
    
    return 0;
}