using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static string[] NList => ReadLine().Split().ToArray();
    static string[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var arr = NArr(n);
        for (var i = 0; i < n; ++i)
        {
            var s = true;
            var t = true;
            for (var j = 0; j < n; ++j)
            {
                if (i == j) continue;
                if (arr[i][0] == arr[j][0] || arr[i][0] == arr[j][1]) s = false;
                if (arr[i][1] == arr[j][0] || arr[i][1] == arr[j][1]) t = false;
            }
            if (!s && !t)
            {
                WriteLine("No");
                return;
            }
        }
        WriteLine("Yes");
    }
}