Friendlist Maintenance

using System;
using System.Collections.Generic;
using System.Linq;

namespace FriendlistMaintenence
{
    class Program
    {
        static void Main(string[] args)
        {
            List<string> usernames = Console.ReadLine().Split(", ").ToList();
            int blacklisted = 0;
            int lost = 0;

            while (true)
            {
                string line = Console.ReadLine();
                if (line == "Report")
                {
                    break;
                }

                string[] input = line.Split();

                switch (input[0])
                {
                    case "Blacklist":
                        string name = input[1];
                        if (usernames.Contains(name))
                        {
                            for (int i = 0; i < usernames.Count; i++)
                            {
                                if (usernames[i] == name)
                                {
                                    usernames[i] = "Blacklisted";
                                }
                            }
                            Console.WriteLine($"{name} was blacklisted.");
                        }
                        else
                        {
                            Console.WriteLine($"{name} was not found.");
                        }
                        break;
                    case "Error":
                        int index = int.Parse(input[1]);
                        string currentName = usernames[index];
                        if (currentName != "Blacklisted" && currentName != "Lost" && index >= 0 && index < usernames.Count)
                        {
                            for (int i = 0; i < usernames.Count; i++)
                            {
                                if (usernames[i] == currentName)
                                {
                                    usernames[i] = "Lost";
                                }
                            }
                            Console.WriteLine($"{currentName} was lost due to an error.");
                        }
                        break;
                    case "Change":
                        int givenIndex = int.Parse(input[1]);
                        string newName = input[2];
                        string current = usernames[givenIndex];

                        if (givenIndex >= 0 && givenIndex < usernames.Count)
                        {
                            usernames[givenIndex] = newName;
                            Console.WriteLine($"{current} changed his username to {newName}.");
                        }
                        break;
                }
            }
            foreach (var item in usernames)
            {
                if (item == "Blacklisted")
                {
                    blacklisted++;
                }
                if (item == "Lost")
                {
                    lost++;
                }
            }
            Console.WriteLine($"Blacklisted names: {blacklisted}");
            Console.WriteLine($"Lost names: {lost}");
            Console.WriteLine(string.Join(" ", usernames));
        }
    }
}