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:
//「合成抵抗」(https://beta.atcoder.jp/contests/cf16-relay-open/tasks/relay_a)

#include<iostream>


int main(){
	//標準入力
	int r[2];
	std::cin>>r[0]>>r[1];

	//処理
	//1/R3=1/R1+1/R2
	//これを加工してR3=R1R2/(R1+R2)
	double ans=r[0]*r[1];//計算誤差を抑えるため、計算結果の途中経過をdoubleにしておく
	ans=ans/(r[0]+r[1]);

	//出力
	//std::cout<<ans<<std::endl;//桁数の指定がめんどいのでprintfに
	printf("%.8f",ans);

	return 0;
}