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<iomanip>
#include<string>


#define rep(i,n) for(int i = 0; i < n; ++i)
using namespace std;

int main(void){
  int r1, r2;
  cin >> r1 >> r2;
  cout << setprecision(9);
  cout << 1.0/(1.0/r1 + 1.0/r2) << endl;
  return 0;
}