import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner scan = new Scanner(System.in);
        long n = scan.nextLong();
        long m = scan.nextLong();
        long result =0;
        if(n==1 & m==1) result = 0;
        if (m==1) result = n-1;
        else if(n==1) result = m-1;
        else if(n>=m) result = (n-1)+n*(m-1);
        else result = (m-1)+m*(n-1);
      System.out.print(result);
    }
}