Coderforces Domino piling

http://codeforces.com/problemset/problem/50/A

import java.util.Scanner;

public class Domino_piling {

public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int m =scanner.nextInt();
int n = scanner.nextInt();
System.out.println(m*n/2);
}
}