using System;

public class Program

{

    static private double avg(double a, double b, double c, double d)

    {

        double total = a+b+c+d;

        return total/4;

    }

    public static void Main()

    {

        Console.WriteLine("1st number:");

        double first = double.Parse(Console.ReadLine());

        Console.WriteLine("2nd number:");

        double second = double.Parse(Console.ReadLine());

        Console.WriteLine("3rd number:");

        double third = double.Parse(Console.ReadLine());

        Console.WriteLine("4th number:");

        double fourth = double.Parse(Console.ReadLine());

        Console.WriteLine("Average: " + avg(first, second, third, fourth));

    }

}