using System;

public class Program

{

    public static void Main()

    {

double R1,R2,R3,E;

    Console.WriteLine("ENTER R1");

        R1 = double.Parse(Console.ReadLine());

    Console.WriteLine("ENTER R2");

            R2 = double.Parse(Console.ReadLine());

    Console.WriteLine("ENTER R3");

            R3 = double.Parse(Console.ReadLine());

    Console.WriteLine("ENTER MAKUR(E)");

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

double R12 = (R1*R2)/(R1+R2);

double Rt = (R12*R3)/(R12+R3);

    Console.WriteLine("Rt IS " + Rt);

double It = (E/Rt);

    Console.WriteLine("It IS " + It);

 }

}