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

namespace aruszallitas_nemes01
{
    internal class Program
    {
        static void Main(string[] args)
        {
            int[] st = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int N = st[0];
            int M = st[1];
            int[] E = new int[M];
            int[] V = new int[M];
            for (int i = 0; i < M; i++)
            {
                st = Console.ReadLine().Split().Select(int.Parse).ToArray();
                E[i] = st[0];
                V[i] = st[1];
            }
            Array.Sort(E, V);
            int db = 0;
            if (E[0] != 1) { db++; }
            int e = E[0], v = V[0];
            for (int i = 1; i < M; i++)
            {
                if (e == E[i] || E[i] <= v)
                {
                    if (v < V[i])
                    {
                        v = V[i];
                    }
                }
                else  
                {
                    db++;
                    e = E[i];
                    v = V[i];
                }
            }
            if (v != N)
            {
                db++;
            }
            Console.WriteLine(db);
        }
    }
}