using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication15
{


    class Program
    {
        static void Main(String[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            Dictionary<int, int> listY = new Dictionary<int, int>();
            Dictionary<int, int> listX = new Dictionary<int, int>();
            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 (!listY.ContainsKey(y))
                {
                    listY.Add(y,1);
                }
                if (!listX.ContainsKey(x))
                {
                    listX.Add(x, 1);
                }
            }
            if (listY.Count == n&&listX.Count==1)
            {
                Console.WriteLine("YES");
            }
            else if (listX.Count == n && listY.Count == 1)
            {
                Console.WriteLine("YES");
            }
            else
            {
                Console.WriteLine("NO");
            }
            Console.Read();

        }
    }
}