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

public class Solution {

    public static void main(String[] args) throws IOException{
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        BufferedReader scan = new BufferedReader(new InputStreamReader(System.in));
        String s[] = scan.readLine().split(" ");
        long ans = Long.parseLong(s[0])*Long.parseLong(s[1]);
        System.out.println(ans-1);
    }
}