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 CPP):

Solution:
#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
 
using namespace std;
 
int main()
{
    double R1, R2;
    if (scanf("%lf%lf", &R1, &R2) < 2) return 0;
 
    printf("%.10lf\n", R1 * R2 / (R1 + R2));
    return 0;
}