Bounce

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int m = in.nextInt();


        long[][] matrix = new long[n][m];

        long startValue = 1;
        for (int row = 0; row < n; row++) {
            for (int col = 0; col < m; col++) {
                matrix[row][col] = startValue;
                if (col < m - 1) {
                    startValue *= 2;
                }
            }
            startValue = matrix[row][1];
        }

        int dirRow = 1;
        int dirCol = 1;
        int currentRow = 0;
        int currentCol = 0;
        long sum = matrix[currentRow][currentCol];
        int nextRow = 0;
        int nextCol = 0;

        if (n == 1 || m == 1) {
            System.out.println(matrix[0][0]);
        } else {
            while (true) {
                nextRow = currentRow + dirRow;
                nextCol = currentCol + dirCol;
                if ((nextRow == 0 || nextRow == n - 1) && (nextCol == 0 || nextCol == m - 1)) {
                    sum += matrix[nextRow][nextCol];
                    System.out.println(sum);
                    break;
                }

                if (nextRow == 0 || nextRow == n - 1) {
                    dirRow *= -1;
                }
                if (nextCol == 0 || nextCol == m - 1) {
                    dirCol *= -1;
                }

                currentRow = nextRow;
                currentCol = nextCol;
                sum += matrix[currentRow][currentCol];
            }
        }
    }
}