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

class yuki301
{
    static int[] NList => Console.ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NMap(int n) => Enumerable.Repeat<int>(0, n).Select(_ => NList).ToArray();
    static void Main()
    {
        var c = NList;
        var (n, m) = (c[0], c[1]);
        var map = NMap(m);

        Array.Sort(map, (a, b) => a[1].CompareTo(b[1]));
        var pos = 0;
        var res = 0;
        while (pos < m)
        {
            ++res;
            var right = map[pos][1];
            while (pos < m && map[pos][0] <= right) ++pos;
        }
        WriteLine(n - res);
    }
}