class Program
{
    static void Main(string[] args)
    {
        var list = new LinkedList<int>();
        list.AddLast(2);
        list.AddLast(1);
        list.AddLast(1);
        list.AddLast(2);

        Console.WriteLine(IsPalindrome(list));
    }

    static bool IsPalindrome(LinkedList<int> list)
    {
        if (list.Count == 0)
            return false;

        if (list.Count == 1)
            return true;

        var halfList = list.Count / 2;
        var current = list.First;
        var stack = new Stack<int>();

        while (halfList > 0)
        {
            stack.Push(current.Value);
            current = current.Next;
            halfList--;
        }

        var isOdd = (list.Count % 2) != 0;
        if (isOdd)
            current = current.Next;

        while(stack.Count != 0)
        {
            if (stack.Pop() != current.Value)
                return false;

            current = current.Next;
        }

        return true;
    }
}