using System;
using System.Collections.Generic;
using System.IO;

class Solution
{
    static void Main(String[] args)
    {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution */

        int howmany = int.Parse(Console.ReadLine());
        string[] s = new string[howmany];
        for (int i = 0; i < howmany; i++)
        {
            s[i] = Console.ReadLine();
        }
        var answer = true;
        for (int i = 1; i < howmany; i++){
            int x1 = int.Parse(s[i-1].Split(' ')[0]);
            int y1 = int.Parse(s[i-1].Split(' ')[1]);
            int x2 = int.Parse(s[i].Split(' ')[0]);
            int y2 = int.Parse(s[i].Split(' ')[1]);
            if ((x1 - x2) * (y1 - y2) != 0) { answer = false; break; }
        }
        Console.WriteLine(answer ? "YES" : "NO");
    }

}