AnonymousTreat-withStringBuilder()

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

namespace AnonimusTreat
{
    class Program
    {
        static void Main(string[] args)
        {
            var list = Console.ReadLine().Split().ToList();

            string command = string.Empty;
            while ((command = Console.ReadLine()) != "3:1")
            {
                string[] commandArray = command.Split();
                if (commandArray[0] == "merge")
                {
                    int startIndex = int.Parse(commandArray[1]);
                    int validCurrentStartIndex = Math.Max(0, startIndex);
                    int validStartIndex = Math.Min(list.Count - 1, validCurrentStartIndex);
                    int endIndex = int.Parse(commandArray[2]);
                    int validCurrentEndIndex = Math.Max(0, endIndex);
                    int validEndIndex = Math.Min(list.Count - 1, validCurrentEndIndex);

                    string stringForMerge = string.Empty;
                    int CountToRemove = validEndIndex - validStartIndex+ 1;
                    for (int i = validStartIndex; i <= validEndIndex; i++)
                    {
                        stringForMerge += list[i];
                    }

                    list.RemoveRange(validStartIndex, CountToRemove);
                    list.Insert(validStartIndex, stringForMerge);
                }

                else if (commandArray[0] == "divide")
                {
                    int index = int.Parse(commandArray[1]);
                    int validCurrentIndex = Math.Max(0, index);
                    int validIndex = Math.Min(validCurrentIndex, list.Count - 1);
                    int partitions = int.Parse(commandArray[2]);
                    string stringForDivide = list[validIndex];
                    var sb = new StringBuilder(stringForDivide);
                    if (sb.Length % partitions == 0)
                    {
                        int lengthDivide = sb.Length / partitions;
                        int indexDivide = lengthDivide;
                        for (int i = 0; i <= sb.Length  - lengthDivide; i++)
                        {
                            if (i == indexDivide)
                            {
                                sb.Insert(i, " ");
                                indexDivide += lengthDivide + 1;
                            }
                        }
                    }

                    else if (sb.Length % partitions != 0)
                    {
                        int lengthDivide = sb.Length / partitions;
                        int indexDivide = lengthDivide;
                        int lastPartitionLength = sb.Length- (lengthDivide * (partitions-1));
                        for (int i = 0; i <= sb.Length - lastPartitionLength; i++)
                        {
                            if (i == indexDivide)
                            {
                                sb.Insert(i, " ");
                                indexDivide += lengthDivide + 1;
                            }
                        }
                    }

                    list.RemoveAt(index);
                    list.InsertRange(index, sb.ToString().Split());
                }
            }

            Console.WriteLine(string.Join(" ",list));
        }
    }
}