using System;
using System.Collections.Generic;

namespace test
{
    static class Program
    {
        static void Main()
        {
            string[] a = Console.ReadLine().Split(' ');
            long n = long.Parse(a[0]);
            long m = long.Parse(a[1]);
            bool[] hairu = new bool[n];
            for(long i = 0;i < m; i++)
            {
                long deguti = long.Parse(Console.ReadLine().Split(' ')[1]);
                hairu[deguti-1] = true;
            }
            long count = 0;
            for(long i = 0;i < n; i++)
            {
                if (hairu[i] == false) count++;
            }
            Console.WriteLine(count);
        }
    }
}