Average train speed

Very easy

Execution time limit is 1 second

Runtime memory usage limit is 128 megabytes

Find the average speed of the train, if it traveled the first half of the distance at a speed of $v_{1}$ , and the second half at a speed of $v_{2}$ .

Input

Two integers $v_{1}$ and $v_{2} (1 \leq v_{1}, v_{2} \leq 1 0^{9})$ .

Output

Print the average speed of the train with $4$ decimal places.

Examples

Input #1

Answer #1

Input #2

Answer #2

Submissions 1K

Acceptance rate 35%