using System;

using System.Text;

public class Program

{

    public static void Main()

    {

        //Console.WriteLine("Hello World");

    }

    public bool IsPalindrome(string s) {

        //  define the start of the string

        int i = 0;

        //  define the end of the string

        int j = s.Length - 1;

        //  Format the string to all lower case

        s = s.ToLower();

        //  iterate through the string while the the beginning of the string is still smaller than the end of the string (two pointer?)

        while (i < j) {

            // if the character is NOT a letter or digit when examingint he character at the beginning of s (i), then increase i by 1 (moves pointer forwards and ignores white space or special chars)

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

                i++;

            }

            //  else if the char is NOT a letter or digit when examining the char at the end of s (j), then subtract j by 1 (moves pointer backwards and ignores white space or special chars)

            if (!char.IsLetterOrDigit(s[j])) {

                j--;

            }

            //  else if the position of current iterated value within s + 1 does not equal the position of j -1, then return false (means the string may have not had many, if not at all, non special characters or white space)

            if (s[i++] != s[j--]) {

                return false;

            }

            return true;

        }

        //  now that the above procedure has removed all anti criteria from the input, we can return true

        return true;

    }

}