using System;

namespace ConsoleApp11
{
    class Program
    {
        static void Main(string[] args)
        {
            ulong count = 0;

            ulong N = ulong.Parse(Console.ReadLine());
            ulong M = ulong.Parse(Console.ReadLine());

            if((N / M) % 1000 == 0)
            {
                Console.WriteLine(N / M);
            }
            else if(N / M >= 1000)
            {
                while (M * 1000 <= N)
                {
                    N -= M * 1000;
                    count++;
                }
                Console.WriteLine(count * 1000);
            }
            else
            {
                Console.WriteLine(0);
            }
            

            
        }
    }
}