using System;

public class PortugalTaxIdentificationNumber

{

    public static void Main()

    {

        bool isValid = isValidPTIN("299999998");

        Console.WriteLine(isValid);

    }

    private static int getReminder(string ntin)

    {

        int addition = 0;

        for (int i=0;i<ntin.Length;i++)

        {

            addition += (Convert.ToInt32(ntin[i]) - 48) * (9 - i);

        }

        int answer = addition % 11;

        answer = 11 - answer;

        if (answer == 10 || answer == 11) return 0;

        return answer;

    }

    private static bool isValidPTIN(string ptin)

    {

        if (ptin.Length != 9) return false;

        foreach(char ch in ptin)

        {

            if (char.IsLetter(ch)) return false;

        }

        int wholestring_check = Convert.ToInt32(ptin[ptin.Length - 1]) - 48;

        string wholestring = ptin.Substring(0,ptin.Length - 1);

        int wholestring_reminder = getReminder(wholestring);

        if (wholestring_reminder != wholestring_check) return false;

        return true;

    }

}