ZigZag

import java.util.Scanner;

public class ZigZag {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int rows = scanner.nextInt();
        int cols = scanner.nextInt();

        long sum = 0;
        for (int i = 0; i < rows; i++) {
            if (i % 2 == 0) {
                for (int j = 0; j < cols; j += 2) {
                    sum += ((j * 3) + (i * 3) + 1);
                    if (i != 0 && i != rows - 1 && j != 0 && j != cols - 1) {
                        sum += ((j * 3) + (i * 3) + 1);
                    }
                }
            } else {
                for (int j = 1; j < cols; j += 2) {
                    sum += ((j * 3) + (i * 3) + 1);
                    if (i != 0 && i != rows - 1 && j != 0 && j != cols - 1) {
                        sum += ((j * 3) + (i * 3) + 1);
                    }
                }
            }
        }

        System.out.println(sum);

    }
}