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 PYTHON):

Solution:
def solve(r1, r2):
    return float(r1*r2) / (r1+r2)
assert abs(solve(2, 3) - 1.2000000000) < 1e-6
assert abs(solve(100, 99) - 49.7487437186) < 1e-6
r1, r2 = map(int, raw_input().split())
print solve(r1, r2)