Problem:
Score : 100 points

Problem Statement

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.

Constraints

1 \leq |AB|,|BC|,|CA| \leq 100

All values in input are integers.

The area of the triangle ABC is an integer.

Input

Input is given from Standard Input in the following format:

|AB| |BC| |CA|

Output

Print the area of the triangle ABC.

Sample Input 1

3 4 5

Sample Output 1

6

This triangle has an area of 6.

Sample Input 2

5 12 13

Sample Output 2

30

This triangle has an area of 30.

Sample Input 3

45 28 53

Sample Output 3

630

This triangle has an area of 630.

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)


import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

class Main {
	
	public static void main(String args[])
	{
		Main col = new Main();
		Scanner sc = new Scanner(System.in);
		int input = sc.nextInt();
		List<Integer> number = new ArrayList<Integer>();
		number.add(input);
		int minimum = 1000000;
		for(int i = 1; i<= 100; i++)
		{
			int result;
			if(number.get(i-1) % 2 == 0)
				result = col.evenNumbers(number.get(i-1));
			else
				result = col.oddNumbers(number.get(i-1));
			
			if(number.contains(result) && result < minimum) {
				minimum = i+1;
				break;
			}
			number.add(result);
		}
		System.out.print(minimum);
		
	}
	
	public int oddNumbers(int x) {
		return 3*x + 1;
	}
	
	public int evenNumbers(int x) {
		return x/2;
	}
}