using System;

namespace NumberGuess
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Enter a number");

            int n1 = int.Parse(Console.ReadLine());

            double n2 = (double) n1 * 2;

            double n3 = n2 + 5;

            double n4 = n3 / 2;

            double n5 = n4 - n1;

            Console.Write(n5);

            Console.ReadLine();
        }
    }
}