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. */
        BufferedReader in = null;
        long answer = 0;
        try {
            
            in = new BufferedReader(new InputStreamReader(System.in));
            String[] input = in.readLine().split(" ");
            long n = Integer.parseInt(input[0]);
            long m = Integer.parseInt(input[1]);
            answer = n * m - 1;
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                in.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
                
        }
        System.out.println(answer);
    }
}