using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {

    static void Main(String[] args) {
        string[] tokens = Console.ReadLine().Split(' ');
            int a = Convert.ToInt32(tokens[0]);
            int b = Convert.ToInt32(tokens[1]);

            int x = 0;

            if ((a == 1) && (b == 1))
            {
                x = 0;
            }
            else if (a == 1)
            {
                x = b - 1;
            }
            else if (b == 1)
            {
                x = a - 1;
            }
            else
            {
                x = (a - 1) + (a * (b - 1));
            }

            Console.WriteLine(x);
    }
}