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 input = new Scanner(System.in);
        long m = input.nextLong();
        long n = input.nextLong();
        long total = 0l;
        total = m-1;
        total = total + (m*(n-1));
        System.out.println(total);
    }
}