using System;
using System.Collections.Generic;

namespace Yuki
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] ss = Console.ReadLine().Split();
            int n = int.Parse(ss[0]);
            int m = int.Parse(ss[1]);
            var li = new List<bool[]>();
            bool[] a = new bool[m];
            li.Add(a);

            for (int i = 0; i < n; i++)
            {
                var li2 = new List<bool[]>();
                ss = Console.ReadLine().Split();
                int L = int.Parse(ss[0]);
                int R = int.Parse(ss[1]);

                foreach (var item in li)
                {
                    bool[] item2 = (bool[])item.Clone();
                    bool f = true;
                    for (int s = L; s <= R; s++)
                    {
                        if (item2[s])
                        {
                            f = false;
                            break;
                        }
                        else
                        {
                            item2[s] = true;
                        }
                    }
                    if (f) li2.Add(item2);

                    f = true;
                    int L2 = m - 1 - R;
                    int R2 = m - 1 - L;
                    if (L == L2 && R == R2)
                    {

                    }
                    else
                    {
                        for (int s = L2; s <= R2; s++)
                        {
                            if (item[s])
                            {
                                f = false;
                                break;
                            }
                            else
                            {
                                item[s] = true;
                            }
                        }
                        if (f) li2.Add(item);
                    }
                }

                li = li2;
            }
            if (li.Count == 0) Console.WriteLine("NO");
            else Console.WriteLine("YES");
        }
    }
}