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

public class Solution {

    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        long n=sc.nextLong();
        long m=sc.nextLong();
        //int l=Math.max(n,m);
        //int cuts=l-1
        System.out.println(n*m-1);
    }
}