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:
#include<iostream>
#include<cstdio>
using namespace std;
int main ()
{
    int r1,r2;
    double r3 ;
    scanf("%d %d",&r1,&r2);
    if((r1 >= 1 && r1 <= 100) && (r2 >= 1 && r2 <= 100 ))
    {
        r3 = double(1.0/r1) + double(1.0/r2) ;
        r3 = 1.0/r3 ;
        printf("%.10f\n",r3);

    }

    return 0 ;
}