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

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);
        int m=scan.nextInt();
        int n=scan.nextInt();
        
        System.out.println((Math.max(m,n)-1)*(Math.min(m,n))+(Math.min(m,n)-1));
    }
}