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