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 <bits/stdc++.h>

using namespace std;
#define lint long long



int main() {
    double a, b;
    cin >> a >> b;
    
    double c;
    c = 1. / a + 1/ b;
    
    double d;
    d = 1. / c;
    
    constexpr int e = std::numeric_limits<float>::max_digits10;
    cout << setprecision(e) <<  1. / c << endl;
}