import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str[] = in.nextLine().split(" ");
        long n = Long.parseLong(str[0]);
        long m = Long.parseLong(str[1]);
        if(m==1&&n==1){
            System.out.println(0);
        }
        else if(m==1&&n>1){
            System.out.println(n-1);
        }
        else if(n==1&&m>1){
            System.out.println(m-1);
        }
        else {
            System.out.println((n-1)+n*(m-1));
        }
    }
}