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:
// Template {{{
#include <bits/stdc++.h>
#define REP(i,n) for(int i=0; i<(int)(n); ++i)
using namespace std;
typedef long long LL;

#ifdef LOCAL
#include "contest.h"
#else
#define dump(x) 
#endif

const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
inline bool valid(int x, int w) { return 0 <= x && x < w; }

void iostream_init() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.setf(ios::fixed);
    cout.precision(12);
}
//}}}

int main(){
    iostream_init();
    double a, b;
    cin >> a >> b;
    double c = 1.0/(1.0/a + 1.0/b);
    cout << c << endl;
    return 0;
}