题解 | #牛牛的并联电路#

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        double r1 = scanner.nextDouble();
        double r2 = scanner.nextDouble();
        System.out.println(1 / ((1 / r1) + (1 / r2)));
    }
}