import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int h = sc.nextInt();
		int w = sc.nextInt();
		sc.close();

		long ans = h + w - 2;
		int n2 = n / 2;
		ans *= n2;
		ans *= n - n2;
		System.out.println(ans);
	}
}