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;

class Program
{
    static void Main(string[] args)
    {
        string a = Console.ReadLine();
        bool flag = true;
        for (int i = 0; i < a.Length; i++)
        {

            if (a[a.Length - 1 - i] == 'b' && a[i] == 'd') { }
            else if (a[a.Length - 1 - i] == 'd' && a[i] == 'b') { }
            else if (a[a.Length - 1 - i] == 'q' && a[i] == 'p') { }
            else if (a[a.Length - 1 - i] == 'p' && a[i] == 'q') { }
            else { flag = false; break; }
        }
        Console.WriteLine(flag ? "Yes" : "No");
        Console.ReadLine();
    }
}