using System;

using System.Runtime;

public class Program

{

    public static void Main()

    {

        string text = "[IP Осв.-Каб.]-2*[IP Осв.-Каб.]+[Мест.пост.этаж]-32*[Нал.код.Брайля кн.в ПУ]";

        int indexEnd = 0;        

        int indexStart = 0;        

        int selectedIndex = 75;

​

                if (selectedIndex != 0)

                {

                    if (text[selectedIndex] == ']')

                    {

                        indexEnd = selectedIndex;

                        for (int i = selectedIndex; i > 0; i--)

                        {

                            if (text[i] == '[')

                            {

                                indexStart = i;

                                break;

                            }

                        }

                    }

                    else

                    {

                        for (int i = selectedIndex; i < text.Length; i++)

                        {

                            if (text[i] == ']')

                            {

                                indexEnd = i + 1;

                                break;

                            }

                        }

​

                        for (int i = selectedIndex; i > 0; i--)

                        {

                            if (text[i] == '[')

                            {

                                indexStart = i;

                                break;

                            }

                        }

                    }

                }

​

        Console.WriteLine($"{indexStart},{indexEnd} - {text.Length} \n {text.Remove(indexStart,indexEnd +1 - indexStart)}");

    }

}