Problem:
Score : 100 points

Problem Statement

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}.

Sample Input 1

2 3

Sample Output 1

1.2000000000

Sample Input 2

100 99

Sample Output 2

49.7487437186

Solution in Ruby (2.7.1) (judge verdict: Accepted)

class CombinedResistance
  def initialize(rs)
    @r1 = rs[0].to_f
    @r2 = rs[1].to_f
  end

  def solve
    @r1 * @r2 / (@r1 + @r2)
  end
end

def run
  rs = gets.scan(/\d+/).map(&:to_i)
  puts CombinedResistance.new(rs).solve
end

run