using System;

public class Program

{

    public static void Main()

    {

            double a,b,c,d;

            Console.Write("enter a:");

            a=Convert.ToDouble(  Console.ReadLine());

            Console.Write("enter b:");

            b=Convert.ToDouble(  Console.ReadLine());

​

            Console.Write("enter c:");

            c=Convert.ToDouble(  Console.ReadLine());

​

            Console.Write("enter d:");

            d=Convert.ToDouble(  Console.ReadLine());

            double e=(a+b+c+d)/4;

            Console.WriteLine(e);

                }

}