using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        bool est = IsRutOk("18767087K");

        Console.WriteLine(est ? "true" : "false");

    }

    public static bool IsRutOk(string rut)

    {

        const string RutRegex = "[0-9]+K?";

        Regex RegExRut = new Regex(RutRegex, RegexOptions.Compiled | 

        RegexOptions.IgnoreCase);

        int[] coefs = {3, 2, 7, 6, 5, 4, 3, 2};

        // In case that rut is padded with spaces

        rut = rut.Trim().ToUpperInvariant();

        if (!RegExRut.IsMatch(rut)) { return false; }

        if (rut.Length > 9) { return false; }

        // If shorter than 9 characters (8 + control char) ...

        while (rut.Length < 9) { rut = "0" + rut; }

        int total = 0;

        for (int index = 0; index < rut.Length - 1; index++)

        {

             char curr = rut.Substring(index, 1).ToCharArray()[0];

             total += coefs[index]*(curr - '0');

        }

        int rest = 11 - (total%11);

        if (rest == 11) rest = 0;

        if ((rest == 10) && rut.EndsWith("K")) { return true; }

        if (rut.Substring(rut.Length - 1, 1).ToCharArray()[0] == ('0' + rest))

        { 

            return true; 

        }

        return false;

    }

}