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(m*(n-1)+(m-1));
    }
}