Description

For resistors with resistances $r_1$ and $r_2$, the formula for calculating the equivalent resistance in parallel is: $R=\dfrac{1}{\frac{1}{r_1}+\frac{1}{r_2}}$
Input the resistance values of two resistors as floating-point numbers. Output the equivalent resistance in parallel, rounded to 2 decimal places.

Input Format

Input consists of two floating-point numbers representing the resistance values of the two resistors, separated by a space.

Output Format

Output the equivalent resistance in parallel, rounded to 2 decimal places.

Sample

1 2

0.67