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 horizontal = true;
        int prevX = 0, prevY = 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(a0 != 0)
            {
                if(a0 == 1) //choosing direction
                {
                    if (x == prevX)
                        horizontal = false;
                    else if (y == prevY)
                        horizontal = true;
                    else
                    {
                        Console.WriteLine("NO");
                        return;
                    }
                }
                else
                {
                    if (horizontal)
                    {
                        if(prevY != y)
                        {
                            Console.WriteLine("NO");
                            return;
                        }

                    }
                    else
                    {
                        if(prevX != x)
                        {
                            Console.WriteLine("NO");
                            return;
                        }
                    }

                }
            }

            prevX = x;
            prevY = y;
        }


        Console.WriteLine("YES");
    }
}