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 <bits/stdc++.h>

#define mp       make_pair
#define mt	  make_tuple
#define rep(i,n) for(int i=0;i<(n);i++)

using namespace std;

using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;

const int INF=1<<29;
const double EPS=1e-9;
const ll MOD = 1000000007;

const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
double R1,R2;
int main(){
  cin >> R1 >> R2;
  double res = (R1 * R2) / (R1 + R2);
  printf("%.20lf\n", res);
  return 0;
}