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>
const int INF=1e9;
const int MOD=1e9+7;
//const int MOD=998244353;
const long long LINF=1e18;
using namespace std;
#define int long double
//template

//main
signed main(){
  int a,b;cin>>a>>b;
  a=1/a;b=1/b;
  a+=b;
  a=1/a;
  cout<<fixed<<setprecision(12)<<a<<endl;
}