#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 n;
    cin>>n;
    int x,y,x2,y2,flag=0;
    cin>>x>>y;
    cin>>x2>>y2;
    if(x==x2)
      {
        flag=1;
    }
    else if(y==y2)
        {
        flag=2;
    }
    else
        flag=3;
    n=n-2;
        while(n)
        {
        
        int a,b;
        cin>>a>>b;
            if(flag==1)
                {
                if(a==x)
                {}
                else
                {flag=3;
                    break;}
               }
            else if(flag==2)
                {
                if(b==y)
                {}
                else
                {flag=3;
                    break;}
            }
            else
                {
                flag=3;
                break;
            }
            
            n=n-1;
    }
    
    if(flag==3)
        {
        cout<<"NO"<<endl;
        
    }
    else
        cout<<"YES";
    return 0;
}