Contest: Task: Related: TaskB

Score : $100$ points

There is a right triangle $ABC$ with $∠ABC=90°$.

Given the lengths of the three sides, $|AB|,|BC|$ and $|CA|$, find the area of the right triangle $ABC$.

It is guaranteed that the area of the triangle $ABC$ is an integer.

- $1 \leq |AB|,|BC|,|CA| \leq 100$
- All values in input are integers.
- The area of the triangle $ABC$ is an integer.

Input is given from Standard Input in the following format:

$|AB|$ $|BC|$ $|CA|$

Print the area of the triangle $ABC$.

3 4 5

6

This triangle has an area of $6$.

5 12 13

30

This triangle has an area of $30$.

45 28 53

630

This triangle has an area of $630$.