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<algorithm>
#include<math.h>
#include<cstdio>
#include<ctype.h>
#include<stdio.h>
#include<set>
#include<vector>
#include<map>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<numeric>
#include<string>
using namespace std;
typedef long long ll;

ll ds(ll digit) {
	ll res = 0;
	while (digit!=0) {
		res += digit % 10;
		digit /= 10;
	}
	return res;
}
ll MOD = 1000000007;
int main() {
	long double x, y;
	cin >> x >> y;
	long double z = x * y / (x + y);
	cout <<fixed<< setprecision(8)<< z << endl;


}