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