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 scanner = new Scanner(System.in);
int n = scanner.nextInt();
        int m = scanner.nextInt();
scanner.close();
        System.out.println(n*m - 1);
    }
}