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<cstring>
#include<cstdlib>
int main(void){
	double a;
	double b;
	int c;
	double s;
	int x[10000];
	int p;
	int n;
	char d[10000];
	scanf("%lf %lf", &a,&b);
	s = a*b / (a + b);
	printf("%f", s);
	return 0;
}