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 <string>
#include <algorithm>
#include <map>
#include <math.h>
#include <iomanip>
#include <vector>
#include <queue>
#include <functional>
#include <random>
#include <time.h>
using namespace std;
typedef long long int ll;
typedef pair<ll, ll> P;
int main() {
	double a, b;
	cin >> a >> b;
	double ans = (a*b) / (a + b);
	cout << fixed << setprecision(20) << ans << endl;
	return 0;
}