using System;


namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] A = Console.ReadLine().Split(' ');
          float a = int.Parse(A[0]);
          float b = int.Parse(A[1]);
          if (a <= b)
              Console.WriteLine(2);
          else
              Console.WriteLine("{0:#}",a/b*2);
        }
    }
}

your formula is not correct, think of more cases

5 3
the answer is 4

ceil(a/b*2)