Problem_1._Activation_Keys_FinalExam_04._04._20

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

namespace Problem_1._Activation_Keys_FinalExam_04._04._20
{
    class Program
    {
        static void Main(string[] args)
        {
            string key = Console.ReadLine();
            string input = "";

            while ((input = Console.ReadLine()) != "Generate")
            {
                string[] splittedIn = input.Split(">>>");
                string command = splittedIn[0];

                if (command == "Contains")
                {
                    string substr = splittedIn[1];

                    if (key.Contains(substr))
                    {
                        Console.WriteLine($"{key} contains {substr}");
                    }
                    else
                    {
                        Console.WriteLine("Substring not found!");
                    }
                }
                else if (command == "Flip")
                {
                    string secCom = splittedIn[1];
                    if (secCom == "Upper")
                    {
                        int startIndex = int.Parse(splittedIn[2]);
                        int endIndex = int.Parse(splittedIn[3]);

                        if (startIndex >= 0 && endIndex >= 0 && endIndex <= key.Length)
                        {
                            int length = endIndex - startIndex;
                            string newStr = key.Substring(startIndex, length).ToUpper();
                            key = key.Replace(key.Substring(startIndex, length), newStr);
                            Console.WriteLine(key);
                        }
                    }
                    else if (secCom == "Lower")
                    {
                        int startIndex = int.Parse(splittedIn[2]);
                        int endIndex = int.Parse(splittedIn[3]);

                        if (startIndex >= 0 && endIndex >= 0 && endIndex <= key.Length)
                        {
                            int length = endIndex - startIndex;
                            string newStr = key.Substring(startIndex, length).ToLower();
                            key = key.Replace(key.Substring(startIndex, length), newStr);
                            Console.WriteLine(key);
                        }
                    }
                }
                else if (command == "Slice")
                {
                    int startIndex = int.Parse(splittedIn[1]);
                    int endIndex = int.Parse(splittedIn[2]);

                    if (startIndex >= 0 && endIndex >= 0 && endIndex <= key.Length)
                    {
                        int length = endIndex - startIndex;
                        //string newStr = key.Substring(startIndex, length);
                        key = key.Remove(startIndex, length);
                        Console.WriteLine(key);
                    }

                }

            }

            Console.WriteLine($"Your activation key is: {key}");
        }
    }
}