using System;
using System.IO;
using System.Collections;
using System.Text.RegularExpressions;
using System.Collections.Generic;

public class WordCount {
    public static void Main() {
        Console.Write("Enter the name of the file to process: ");
        StreamReader input = new StreamReader(Console.ReadLine());

        Dictionary<string, int> count = new Dictionary<string, int>();
        foreach (string s  in Regex.Split(input.ReadToEnd(), @"[^a-zA-Z']+")) {
            String s2 = s.ToLower();
            if (!count.ContainsKey(s2))
                count[s2] = 1;
            else
                count[s2]++;
        }
        Console.WriteLine("length = " + count.Count);
        foreach (string s in count.Keys)
            if (count[s] >= 500)
                Console.WriteLine(count[s] + "  " + s);
    }
}