using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        int N = int.Parse(Console.ReadLine());
        var set = new HashSet<(int, int)>();

        for (int i = 0; i < N; i++)
        {
            var x = Console.ReadLine().Split();
            int A = int.Parse(x[0]);
            int B = int.Parse(x[1]);

            var key = (A, B);
            if (set.Contains(key))
            {
                Console.WriteLine("Yes");
                return;
            }
            set.Add(key);
        }

        Console.WriteLine("No");
    }
}