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

 class test123 {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long n = in.nextLong();
        long m = in.nextLong();
        long res=(n*m);
        System.out.println(res-1);
    }
}