import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		long n = scan.nextLong();
		long m = scan.nextLong();
		
		scan.close();
		
		long result = n * m - 1;
		
		System.out.println(result);
	}
}