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


int main() 
{
    int n;
    cin>>n;
    float a[n],b[n];
    int flag = 1;
    for( int i = 0 ; i < n ; i++ )
    {
        cin>>a[i]>>b[i];
        
    }
    if( a[0] == a[1] )
    {
         for( int i = 1 ; i < (n-1) ; i++ )
        {
            if(a[i] == a[i+1])
            {
                continue;
            }
             else
             {
                 flag = 0;
                 break;
             }
        }
    }
    else if(b[0] == b[1])
    {
        for( int i = 1 ; i < (n-1) ; i++ )
        {
            if(b[i] == b[i+1])
            {
                continue;
            }
             else
             {
                 flag = 0;
                 break;
             }
        }
    }
    else
    {
        flag = 0;
    }
   
    
    if( flag == 1)
    {
        cout<<"YES";
    }
    else
        {
        cout<<"NO";
    }
    
    return 0;
}