10531: ABC116 —— A - Right Triangle
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Description
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.
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.
Input
Input is given from Standard Input in the following format:
```
$|AB|$ $|BC|$ $|CA|$
```
```
$|AB|$ $|BC|$ $|CA|$
```
Output
Print the area of the triangle $ABC$.
Constraints
- $1 \leq |AB|,|BC|,|CA| \leq 100$
- All values in input are integers.
- The area of the triangle $ABC$ is an integer.
- All values in input are integers.
- The area of the triangle $ABC$ is an integer.
Sample 1 Input
3 4 5
Sample 1 Output
6
This triangle has an area of 6.
Sample 2 Input
5 12 13
Sample 2 Output
30
This triangle has an area of 30.
Sample 3 Input
45 28 53
Sample 3 Output
630
This triangle has an area of 630.