using System;

public class Program

{

    public static void Main()

    {

        string s = "A man, a plan, a canal: Panama";

        Console.WriteLine(checkPalindrome(s)); 

    }

    private static bool checkPalindrome(string s){

        s= s.ToLower();

        string sAlphanumeric = "";

        // removing non alpha numeric here

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

        {

            if(char.IsLetterOrDigit(s[i]))

                sAlphanumeric +=s[i];

        }

        string reverseofs = "";

        for(int i=sAlphanumeric.Length-1; i >=0 ; i--)

        {

                reverseofs +=sAlphanumeric[i];

        }

        if(sAlphanumeric == reverseofs) return true;

        else return false;

    }

}