My Problem 2 (Mid Exam 10/07/2021)

using System;
using System.Linq;
using System.Numerics;
using System.Text;
using System.Collections.Generic;
using System.ComponentModel;
using System.Reflection.Metadata.Ecma335;
using System.Runtime.ExceptionServices;
using System.Threading;
using System.Text.RegularExpressions;

namespace ConsoleApp24
{
    class Program
    {
        static void Main(string[] args)
        {

            List<int> integers= Console.ReadLine().Split().Select(int.Parse).ToList();

            string input = Console.ReadLine();

            while (input != "Finish")
            {
                string[] commands = input.Split();
                int element = int.Parse(commands[1]);

                switch (commands[0])
                {
                    case "Add":
                        integers.Add(int.Parse(commands[1]));
                        break;
                    case "Remove":
                        if (integers.Contains(element))
                        {
                            integers.Remove(element);
                        }
                        break;
                    case "Replace":
                        if (integers.Contains(element))
                        {
                            int element2 = int.Parse(commands[2]);
                            int index = integers.FindIndex(g => g == element);
                            integers.RemoveAt(index);
                            integers.Insert(index, element);
                        }
                        break;
                    case "Collapse":
                        for (int i = 0; i < integers.Count; i++)
                        {
                            if (integers[i] < element)
                            {
                                integers.Remove(integers[i]);
                            }
                        }
                        break;
                }

                input = Console.ReadLine();
            }

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