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