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

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            int N = int.Parse(Console.ReadLine());
            int M = int.Parse(Console.ReadLine());

            Console.WriteLine(N / M - N / M % 1000);
        }
    }
}