Problem: 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}.

Examples

Input

2 3


Output

1.2000000000


Input

100 99


Output

49.7487437186

Solution (in PYTHON3):

Solution:
import math
import sys

def getinputdata():

    # 配列初期化
    array_result = []
    
    data = input()
    
    array_result.append(data.split(" "))

    flg = 1

    try:
        while flg:

            data = input()

            array_temp = []

            if(data != ""):
                
                array_result.append(data.split(" "))

                flg = 1

            else:

                flg = 0
    finally:


        return array_result

arr_data = getinputdata()

r1 = int(arr_data[0][0])
r2 = int(arr_data[0][1])


print(1/((r2+r1) /(r1*r2)))