import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
import java. util. Scanner;

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. */
        long m,n,out;
        Scanner sc =new Scanner(System.in);
        m=sc.nextLong();
        n=sc.nextLong();
        out=m*n-1;
        System.out.println(out);
    }
}