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


class Program
{
    public void Proc()
    {
        Reader.IsDebug = false;
        int[] inpt = Reader.ReadLine().Split(' ').Select(a => int.Parse(a)).ToArray();

        int pointCount = inpt[0];
        int connectCount = inpt[1];

        for (int i = 0; i < connectCount; i++)
        {
            inpt = Reader.ReadLine().Split(' ').Select(a => int.Parse(a)).ToArray();
            if (!con.ContainsKey(inpt[0]))
            {
                con.Add(inpt[0], new Dictionary<int, bool>());
            }
            con[inpt[0]][inpt[1]] = true;
            if (!con.ContainsKey(inpt[1]))
            {
                con.Add(inpt[1], new Dictionary<int, bool>());
            }
            con[inpt[1]][inpt[0]] = true;
        }
        bool ans = GetAns(1, 5);
        Console.WriteLine(ans ? "YES" : "NO");
    }

    private bool GetAns(int pos, int remain)
    {
        if (!dic.ContainsKey(pos))
        {
            dic.Add(pos, new Dictionary<int, bool>());
        }
        if (dic[pos].ContainsKey(remain))
        {
            return dic[pos][remain];
        }

        if (remain == 0)
        {
            return pos == 1;
        }

        bool ans = false;

        if (con.ContainsKey(pos))
        {
            foreach (int next in con[pos].Keys)
            {
                bool ret = this.GetAns(next, remain - 1);
                if (ret)
                {
                    ans = true;
                    break;
                }
            }
        }
        this.dic[pos].Add(remain, ans);
        return ans;
    }

    private Dictionary<int, Dictionary<int, bool>> con = new Dictionary<int, Dictionary<int, bool>>();

    private Dictionary<int, Dictionary<int, bool>> dic = new Dictionary<int, Dictionary<int, bool>>();


    public class Reader
    {
        public static bool IsDebug = true;
        private static String PlainInput = @"





7 10
1 2
1 3
1 4
1 5
2 3
2 4
2 6
3 4
3 7
4 5





";
        private static System.IO.StringReader Sr = null;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (Sr == null)
                {
                    Sr = new System.IO.StringReader(PlainInput.Trim());
                }
                return Sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }
    }
    static void Main()
    {
        Program prg = new Program();
        prg.Proc();
    }
}