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