using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

            FindAllDeviders obj = new FindAllDeviders();

            obj.Run();

    }

}

​

​

    public class FindAllDeviders

    {

        public void Run() {

            int A = 5;

            int B = 20;

            int M = 4;

​

            int start = A + (M - A % M);

            int delta = B - start;

​

            int next = delta/M;

​

            Console.WriteLine(next+1);

            Console.ReadLine();

        }

    }