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());
        int ox = 0;
        int oy = 0;
        bool found = true;
        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(a0==0)
                {
                ox = x;
                oy = y;
            }
            if(ox != x && oy != y){
                found = false;
                break;
            }
        }
        if(found)
            Console.WriteLine("YES");
        else
            Console.WriteLine("NO");
    }
}