# The surface area of the pyramid 2

Execution time limit is 1 second Runtime memory usage limit is 64 megabytes Determine the lateral surface area of the right cut square pyramid from the base of a, b and height h.

## Input

In a single line through the gap by reason of the pyramid a, b and height h. All input data are integers, not exceeding 100.

## Output

The search area, the result output to two decimal places.

## Examples