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 isX = true;
        bool isY = true;
        
        var xAux = 0;
        var yAux = 0;
        
        for(int a0 = 0; a0 < n; a0++){
            string[] tokens_x = Console.ReadLine().Split(' ');
            int x = Convert.ToInt32(tokens_x[0]);
            int y = Convert.ToInt32(tokens_x[1]);
            
            if(x != xAux && isX)
                isX = false;
            
            if(y != yAux && isY)
                isY = false;
        }
        
        if(isX || isY)
            Console.WriteLine("YES");
        else 
            Console.WriteLine("NO");
    }
}