using static System.Console;

public class Program {

    public static void Main() {

        WriteLine(checkPalindrome("ana"));

        WriteLine(checkPalindrome("abba"));

        WriteLine(checkPalindrome("oki"));

    }

    static bool checkPalindrome(string inputString) {

        if(inputString.Length >= 1 && inputString.Length <= 100_000) {

            for (var i = 0; i < inputString.Length / 2; i++) if (char.ToLower(inputString[i]) != char.ToLower(inputString[inputString.Length - i - 1])) return false;

            return true;

        }

        return false;

    }

}