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 sn = new Scanner(System.in);
            long n = sn.nextLong();
            long m = sn.nextLong();
            System.out.print(n*m-1);
        }
}