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<cstdio>
#include<iostream>
#include<vector>
#include<string>
#include<algorithm>
#include<queue>
#include<stack>
#include<map>
#include<set>
#include <iomanip>

#define rep0(i,N) for(int i=0;i<N;i++)
#define rep1(i,a,N) for(int i=0+a;i<N;i++)
#define lint long long int
#define SIZE 100005

using namespace std;

int main(){
	double a,b;
	cin>>a>>b;
	cout<< fixed << setprecision(8) <<1/(1/a+1/b);

return 0;
}