using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

class PHPVariables
{
    static void Main()
    {
        StringBuilder text = new StringBuilder();
        StringBuilder result = new StringBuilder();
        HashSet<string> existing = new HashSet<string>();
        string line = Console.ReadLine().Trim();

        while (line != "?>")
        {
            text.AppendLine(line);
            line = Console.ReadLine().Trim();
        }

        bool oneLineComment = false;
        bool moreLineComment = false;
        for (int i = 0; i < text.Length; i++)
        {
            if (text[i].ToString() == "/" || text[i].ToString() == "#")
            {
                oneLineComment = true;
            }
            else if (text[i] == '\n')
            {
                oneLineComment = false;
            }
            else if (text[i].ToString() == "/*")
            {
                moreLineComment = true;
            }
            else if (text[i].ToString() == "*/")
            {
                moreLineComment = false;
            }

            if (!oneLineComment && !moreLineComment)
            {
                if (text[i] == '\\')
                {
                    i += 2;
                }
                if (text[i] == '$')
                {
                    if (char.IsNumber(text[i + 1]) || char.IsLetter(text[i + 1]) || text[i + 1] == '_')
                    {
                        i++;
                        while (char.IsNumber(text[i]) || char.IsLetter(text[i]) || text[i] == '_')
                        {
                            result.Append(text[i]);
                            i++;
                        }
                        existing.Add(result.ToString());
                        result.Clear();
                        i--;
                    }
                }
            }
        }
        //1
        //string[] answer = existing.ToArray();
        //Array.Reverse(answer);
        //Console.WriteLine(existing.Count);
        //Console.WriteLine(string.Join("\n", answer));

        //2
        //StringBuilder answer = new StringBuilder();
        //foreach (var item in existing.OrderBy(x => x))
        //{
        //    answer.AppendLine(item);
        //}
        //Console.WriteLine(existing.Count);
        //Console.Write(answer);

        //3
        List<string> answer = existing.ToList();
        Console.WriteLine(existing.Count);
        Console.WriteLine(string.Join("\n", answer));
    }
}