013. Resistors in Parallel

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

Copy

60
40

output

Copy

24.0

input

Copy

80
70

output

Copy

37.333333333333336