using System;

public class Program

{

  public static void Main()

  {

  Console.WriteLine("nomre  1 :");

  double d1 = Convert.ToDouble(Console.ReadLine());

  Console.WriteLine("vahed 1 :");

  double v1 = Convert.ToDouble(Console.ReadLine());

  d1 *= v1;

  Console.WriteLine("nomre  2 :");

  double d2 = Convert.ToDouble(Console.ReadLine());

  Console.WriteLine("vahed 2 :");

  double v2 = Convert.ToDouble(Console.ReadLine());

  d2 *= v2;

  Console.WriteLine("nomre 3 :");

  double d3 = Convert.ToDouble(Console.ReadLine());

  Console.WriteLine("vahed 3 :");

  double v3 = Convert.ToDouble(Console.ReadLine());

  d3 *= v3;

  double hasel = (d1+d2+d3)/(v1+v2+v3);

  Console.WriteLine("hasel: {0}",hasel);

  }

     }