using System;

public class Program

{

    public static void Main()

    {

        var solution = Solution(9, 18, 3);

        Console.WriteLine("Solution: " + solution);

    }

    public static int Solution(int a, int b, int k){

        int count = 0;

        int div1 = 0;

        int div2 = 0;

        div1 = a / k;

        div2 = b / k;

        count = div2 - div1;

        if(a % k == 0) count++;

        return count;

    }

}