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 in = new Scanner(System.in);
        long n,m;
        n=in.nextInt(); m=in.nextInt();
        System.out.println((n*m-1));
    }
}