import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        Long x = in.nextLong();
        Long y = in.nextLong();
        System.out.println(x * y - 1);
    }
}