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) throws Exception {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        
        BufferedReader reader = new BufferedReader( new InputStreamReader( System.in ) ) ;
        String data = reader.readLine() ;
        
        String [] d = data.split( " " ) ;
        
        long m = Integer.parseInt( d[0] ) ;
        long n = Integer.parseInt( d[1] ) ;
        
        long total = m * n ;
        
        System.out.println( total - 1 ) ;
        
    }
}