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

    static void Main(string[] args)
        {
            int previousX = int.MaxValue;
            int previousY = int.MaxValue;
            bool valid = true;
            int n = Convert.ToInt32(Console.ReadLine());
            for (int a0 = 0; a0 < n; a0++)
            {
                string[] tokensX = Console.ReadLine().Split(' ');
                int x = Convert.ToInt32(tokensX[0]);
                int y = Convert.ToInt32(tokensX[1]);

                valid = valid && IsLineOnVarticleOrHorizontal(x, y, ref previousX, ref previousY);
            }


            Console.WriteLine("{0}", valid ? "YES" : "NO");
            Console.ReadLine();
        }

        static bool IsLineOnVarticleOrHorizontal(int x, int y, ref int previousX, ref int previousY)
        {

            if (( previousX == int.MaxValue) && (previousY == int.MaxValue))
            {
                previousX = x;
                previousY = y;
                return true;
            }

            if ((x == previousX) | (y == previousY))
            {
                previousX = x;
                previousY = y;
                return true;
            }
            return false;
        }
}