using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

    public class StringTrie

    {

        private Node head = new Node();

​

        public void Insert(string s)

        {

            Node curr = head;

            foreach(char c in s)

            {

                Node next;

                if (!curr.nodes.TryGetValue(c, out next))

                {

                    curr.nodes.Add(c, next = new Node());

                }

​

                curr = next;

            }

            curr.StringValue = s;

        }

​

        private class Node

        {

            public Dictionary<char, Node> nodes = new Dictionary<char, Node>();

            public bool IsLeaf { get { return nodes.Count == 0; } }

            public string StringValue;

        }

    }

}