using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Console.WriteLine("SilverLining: "+ ThirdExercise(1));

        Console.WriteLine("SilverLining: "+ ThirdExercise(2));

        Console.WriteLine("Valid Chracter: "+ IsValidCharacter("(', ')"));

        Console.Write("Is Palindrome: "+ IsPalindrome("A man, a plan, a canal: Panama").ToString());

    }

    public static bool IsPalindrome(string stringInQuestion)

    {

        return stringInQuestion == ReverseString(stringInQuestion);

    }

    public static string ReverseString(string stringInQuestion)

    {

        var reversedString = "";

        var individualCharacters = stringInQuestion.ToCharArray().ToList().Where(s => Char.IsLetter(s)).ToList();

        for(int i = (individualCharacters.Count() - 1); i >= 0; i--)

        {

            reversedString += individualCharacters[i];

        }

        return reversedString;

    }

    public static bool IsValidCharacter(string character)

    {

        var charArray = character.ToCharArray().ToList();

        var firstOpening = character.First();

        var lastClosing = character.Last();

        return firstOpening == lastClosing;

    }

    public static string ThirdExercise(int number)

    {

        var returnedString = "";

        if(number % 3 == 0)

        {

            returnedString += "Lininhg";

        }

        if(number % 5 == 0)

        {

            returnedString += "Silver";

        }

        return returnedString;

    }

}