Problem:
Score : 100 points

Problem Statement

In an electric circuit, when two resistors R_1 and R_2 are connected in parallel, the equivalent resistance R_3 can be derived from the following formula:

\frac{1}{R_1} + \frac{1}{R_2} = \frac{1}{R_3}

Given R_1 and R_2, find R_3.

Constraints

1 \leq R_1, R_2 \leq 100

R_1 and R_2 are integers.

Input

The input is given from Standard Input in the following format:

R_1 R_2

Output

Print the value of R_3.

The output is considered correct if the absolute or relative error is at most 10^{-6}.

Sample Input 1

2 3

Sample Output 1

1.2000000000

Sample Input 2

100 99

Sample Output 2

49.7487437186

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Linq;

namespace relay_a
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] x = Console.ReadLine().Split().Select(int.Parse).ToArray();
            Console.WriteLine(x[0] * x[1] / (x[0] + x[1]));
        }
    }
}