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>
#define int long long
#define loop(i, a, b) for(int i = a; i < b; i++)
#define rep(i, a) loop(i, 0, a)
#define all(a) (a).begin(),(a).end()
using namespace std;
const int MOD = 1e9 + 7, INF = 1e9;
using vi = vector <int>;
using vvi = vector <vi>;
//g++ -std==c++14

signed main(){
    int a, b;
    cin >> a >> b;
    double r = 1.0 / a + 1.0 / b;
    printf("%.10f\n", 1.0/r);
}