using System;

public class Program

{

    public static void Main()

    {

        double comC,comG,mathC,mathG,engC,engG,GPA;

            Console.Write("input Com credit :");

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

        Console.Write("input Com grade :");

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

            Console.Write("input Math credit :");

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

        Console.Write("input Math grade :");

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

            Console.Write("input Eng credit :");

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

        Console.Write("input Eng grade :");

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

        GPA = (comC*comG + mathC*mathG + engC*engG)/(comC + mathC + engC);

        Console.WriteLine("GPA = {0:F3}",GPA);

    }

}