Anonymous Threat

using System;
using System.Linq;
using System.Globalization;
using System.Numerics;
using System.Collections.Generic;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            string text = Console.ReadLine();
            List<string> words = text.Split().ToList();

            while (true)
            {
                string input = Console.ReadLine();
                if (input == "3:1")
                {
                    break;
                }
                string[] inputList = input.Split();
                string command = inputList[0];
                if (command == "merge")
                {
                    int startIndex = int.Parse(inputList[1]);
                    int endIndex = int.Parse(inputList[2]);
                    if (startIndex >= 0 && startIndex < words.Count && endIndex >= 0)
                    {
                        Merge(words, startIndex, endIndex);
                    }
                }
                else if (command == "divide")
                {
                    int index = int.Parse(inputList[1]);
                    int parts = int.Parse(inputList[2]);
                    Divide(words, index, parts);
                }
            }

            Console.WriteLine(string.Join(" ", words));

        }

        private static void Merge(List<string> words, int startIndex, int endIndex)
        {
            if (startIndex < 0)
            {
                startIndex = 0;
            }
            if (endIndex > words.Count)
            {
                endIndex = words.Count - 1;
            }
            for (int i = startIndex + 1; i <= endIndex; i++)
            {
                words[startIndex] = string.Concat(words[startIndex], words[i]);
                words.RemoveAt(i);
                i--;
                endIndex--;
            }

        }

        private static void Divide(List<string> words, int index, int parts)
        {
            string word = words[index];
            string temp = string.Empty;
            List<string> tempList = new List<string>();
            words.RemoveAt(index);
            for (int i = 0; i < parts; i++)
            {
                if (i == parts - 1)
                {
                    temp = word.Substring(i * (word.Length / parts));
                }
                else
                {
                    temp = word.Substring(i * (word.Length / parts), (word.Length / parts));
                }
                tempList.Add(temp);
            }
            words.InsertRange(index, tempList);
        }
    }
}