import java.io.*;
import java.util.*;
class PaperCut {
    public static void main(String[] args) throws IOException{
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String[] input = in.readLine().split("\\s+");
        long m = Integer.parseInt(input[0]);
        long n = Integer.parseInt(input[1]);
        System.out.println(m*n-1);
    }
}