using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {

    static void Main(String[] args) {
        int n = Convert.ToInt32(Console.ReadLine());bool isCorrect = true;
        string[] tokens_x1 = Console.ReadLine().Split(' ');
        int x1 = Convert.ToInt32(tokens_x1[0]); int y1 = Convert.ToInt32(tokens_x1[1]);
        string[] tokens_x12 = Console.ReadLine().Split(' ');
        int x12 = Convert.ToInt32(tokens_x12[0]); int y12 = Convert.ToInt32(tokens_x12[1]); 
        if(x1==x12){
            
            for(int a0 = 0; a0 < n-2; a0++){
                                                     if(!isCorrect)
                                                     {Console.ReadLine();continue;}
                                else{
            string[] tokens_x = Console.ReadLine().Split(' ');
            int x = Convert.ToInt32(tokens_x[0]);// int y = Convert.ToInt32(tokens_x[1]);
                if(x!=x1){
                    isCorrect=false; 
                }
                                }
        }
            
        }
        else if(y1==y2){
       
        //    else if(y!=y1){
                   // isCorrect=false; 
                            for(int a0 = 0; a0 < n-2; a0++){
                                     if(!isCorrect){
                                         Console.ReadLine();
                                         continue;}
                                else{
            string[] tokens_x = Console.ReadLine().Split(' ');
            int y = Convert.ToInt32(tokens_x[1]);// int y = Convert.ToInt32(tokens_x[1]);
                if(y!=y1){
                    isCorrect=false; 
                }
                                }
        }
                
                
                }
        }
        
        else{
            isCorrect=false; 
            for(int a0 = 0; a0 < n-2; a0++){
                Console.ReadLine();
            }
        }
      if(isCorrect){
          Console.WriteLine("YES");
      }
        else{
            Console.WriteLine("NO");
        }
    }
}