ZigZag

import java.util.Scanner;

public class ZigZag02 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int rows = sc.nextInt();
        int cols = sc.nextInt();

        if (rows == 1 || cols == 1){
            System.out.println(getValue(0,0));
            return;
        }

        long result = getValue(0,0);
        int row = 1;
        int col = 1;
        int dRow = -1;
        int dCol = +1;

        while (!atCorner (row, col, rows, cols)) {
            result += getValue(row, col);

            int nextRow = row;
            int nextCol = col + dCol;
            if (nextCol<0 || nextCol > cols - 1) {
                dCol *= -1;
                dRow*=-1;
            }
            row += dRow;
            col += dCol;
            dRow *= -1;
        }
        result += getValue(row, col);
        System.out.println(result);
    }
    private static long getValue (int row, int col) {
        int sum = row + col;
        return (long) (sum*3)+1;
    }
    private static boolean atCorner(int row, int col, int rows, int cols) {
        return  ((row <= 0 || row >= rows - 1) && (col <= 0 || col >= cols -1));
    }
}