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 JAVA):

Solution:
import java.math.BigDecimal;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        // TODO 自動生成されたメソッド・スタブ

        Scanner sc = new Scanner(System.in);
        BigDecimal one = new BigDecimal(1);

        BigDecimal r1 = new BigDecimal(sc.nextInt());
        BigDecimal r2 = new BigDecimal(sc.nextInt());

        r1 = one.divide(r1,12,BigDecimal.ROUND_UP );
        r2 = one.divide(r2,12,BigDecimal.ROUND_UP );
        BigDecimal r3 = r1.add(r2);
        r3 = one.divide(r3,12,BigDecimal.ROUND_UP);
        System.out.println(r3);

    }

}