User Logs

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

class UserLogs
{
    static void Main()
    {
        string inputLine = Console.ReadLine();
        StringBuilder iPLogs = new StringBuilder();
        SortedDictionary<string, Dictionary<string, int>> output = new SortedDictionary<string, Dictionary<string, int>>();

        while (inputLine != "end")
        {
            iPLogs.Append(inputLine);
            iPLogs.Append("\n\r");
            inputLine = Console.ReadLine();
        }

        Regex regex = new Regex(@"IP=(.+) message=.+ user=(.+)");
        MatchCollection matches = regex.Matches(iPLogs.ToString());

        foreach (Match match in matches)
        {
            Dictionary<string, int> subDictionary = new Dictionary<string, int>();

            string iP = match.Groups[1].ToString();
            string user = match.Groups[2].ToString();

            if (output.ContainsKey(user))
            {
                subDictionary = output[user];
                if (subDictionary.ContainsKey(iP))
                {
                    int repetitions = subDictionary[iP] + 1;
                    subDictionary[iP] = repetitions;
                }
                else
                {
                    subDictionary.Add(iP, 1);
                }

                output[user] = subDictionary;
            }
            else
            {
                subDictionary.Add(iP, 1);
                output.Add(user, subDictionary);
            }
        }

        foreach (var subDictionary in output)
        {
            Console.WriteLine("{0}: ", subDictionary.Key);
            int counter = 1;
            foreach (var ip in subDictionary.Value)
            {
                Console.Write("{0} => {1}", ip.Key, ip.Value);
                if (counter == subDictionary.Value.Count)
                {
                    Console.WriteLine(".");
                }
                else
                {
                    Console.Write(", ");
                }
                counter++;
            }
        }
    }
}