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 scan = new Scanner(System.in);
        long n = scan.nextInt();
        long m = scan.nextInt();
        long ans = m*n-1;
        System.out.println(ans);
    }
}