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 sc=new Scanner (System.in);
        long m=sc.nextLong();
        long n=sc.nextLong();
        System.out.println(n-1+((m-1)*n));
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
    }
}