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:
// header {{{
#include <bits/stdc++.h>
using namespace std;

// {U}{INT,LONG,LLONG}_{MAX,MIN}
#define ALPHABET    (26)
#define INF         INT_MAX
#define MOD         (1000000007LL)

using LL  = long long;
// }}}

int main() {
    std::ios::sync_with_stdio(false);
    double r1, r2;cin >> r1 >> r2;
    printf("%.8f", 1/(1/r1+1/r2));
    return 0;
}