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>
using namespace std; 
const int dx[]={1,0,-1,0,1,-1,-1,1}; 
const int dy[]={0,1,0,-1,1,1,-1,-1}; 
const int INF = 1e9; 
const long long LINF = 1e18; 
const double EPS = 1e-8; 
#define pb push_back
#define mk make_pair 
#define fr first 
#define sc second 
#define ll long long 
#define reps(i,j,k) for(int i = (j); i < (k); ++i) 
#define rep(i,j) reps(i,0,j) 
#define all(a) (a).begin(),(a).end() 
#define MOD 1000000007 
typedef pair<int,int> Pii;
typedef pair<Pii,int> P;
typedef vector<int> vi;

int main(){

	int a , b;
	cin >> a >> b;

	printf("%.8f\n",(double)(a*b)/(double)(a+b));

	return 0;
}