#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int i,t,checkx=0,checky=0;
    cin>>t;
    int a[t][2];
    for(i=0;i<t;i++)
     cin>>a[i][0]>>a[i][1];
    
    for(i=1;i<t;i++)
     {
      if(a[i][0]!=a[i-1][0])
          checkx++;
      if(a[i][1]!=a[i-1][1])
          checky++;
        
     }   
    if((checkx==0)||(checky==0))    
       cout<<"YES\n";
    else cout<<"NO\n";
    return 0;
}