Task Planner 90/100

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

namespace Tasks_Planner
{
    class Program
    {
        static void Main()
        {
            var taskList = Console.ReadLine().Split().ToList();
            string input = Console.ReadLine();

            while(input != "End")
            {
                List<string> command = input.Split().ToList();

                if (command[0] == "Complete" && IsIndexExist(taskList, command))
                {
                    int taskIndex = int.Parse(command[1].ToString());
                    taskList[taskIndex] = "0";
                }
                else if (command[0] == "Change" && IsIndexExist(taskList, command))
                {
                    int taskIndex = int.Parse(command[1].ToString());
                    taskList[taskIndex] = command[2];
                }
                else if (command[0] == "Drop" && IsIndexExist(taskList, command))
                {
                    int taskIndex = int.Parse(command[1].ToString());
                    taskList[taskIndex] = "-1";
                }
                else if(command[0] == "Count")
                {
                    if (command[1] == "Completed")
                    {
                        int count = 0;
                        foreach (var item in taskList.Where(i => i == "0"))
                        {
                            count++;
                        }
                        Console.WriteLine(count);
                    }
                    else if (command[1] == "Incomplete")
                    {
                        int count = 0;
                        foreach (var item in taskList.Where(i => i != "0" && i != "-1"))
                        {
                            count++;
                        }
                        Console.WriteLine(count);

                    }
                    else if (command[1] == "Dropped")
                    {
                        int count = 0;
                        foreach (var item in taskList.Where(i => i == "-1"))
                        {
                            count++;
                        }
                        Console.WriteLine(count);
                    }
                }
                input = Console.ReadLine();
            }
            List<string> newList = new List<string>();
            foreach (var item in taskList.Where(i => i != "0" && i != "-1"))
                {
                newList.Add(item);
            }
            Console.WriteLine(string.Join(" ", newList));

        }
        static bool IsIndexExist(List<string> taskList, List<string> command)
        {
            bool isIndexExist = false;
            int index = int.Parse(command[1].ToString());
            if (index >= 0 && index < taskList.Count)
            {
                isIndexExist = true;
            }
            return isIndexExist;
        }
    }
}