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) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        try{
            BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
            String input = read.readLine();
            String arr[] = input.split(" ");
            long n = Long.parseLong(arr[0]);
            long m = Long.parseLong(arr[1]);
            System.out.println((n*m)-1);
        }catch(Exception e){
            
        }
    }
}