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 <string>
#include <vector>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <typeinfo>
#include <numeric>
#include <functional>
#include <unordered_map>
 
using namespace std;
using ll = long long;
using ull = unsigned long long;
 
const ll INF = 1e16;
const ll MOD = 1e9 + 7;

#define REP(i, n) for(int i = 0; i < n; i++)
#define RREP(i, n) for(int i = n - 1; i >= 0; i--)
#define REP2(i, n, k) for(int i = 0; i < n; i += k)


int main()
{
	double r1, r2;

	cin >> r1 >> r2;

	printf("%.7lf\n", r1 * r2 / (r1 + r2));
}