013. Resistors in Parallel
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

When two resistors with resistances a and b are parallel in an electronic circuit, their equivalent resistance is calculated as (a * b) / (a + b). Given the resistances of two resistors, calculate their equivalent resistance.

Input

The first line of input contains a single positive integer a: the resistance of the first resistor. The second line of input contains a single positive integer b: the resistance of the second resistor.

Output

Output a single positive decimal number r: the equivalent resistance of the two resistors, calculated using the above formula.

Examples
Input
60
40
Output
24.0
Input
80
70
Output
37.333333333333336