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 <stdio.h>
#include <cstdio>
#include <algorithm>

using namespace std;

int main(){
  int r1,r2;
  while(cin>>r1>>r2){
    double r3 = r1*r2*1.0/(r1+r2);
    printf("%.7f\n",r3);
    //cout<<r3<<endl;
  }
  return 0;
}