Lists - Exercises / 03. Array Manipulator

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

namespace Lists
{
    public class Lists
    {
        public static void Main()
        {
            var input = Console.ReadLine().Split(' ').Select(int.Parse).ToList();
            var command = Console.ReadLine().Split(' ').ToList();
            while (command[0] !="print")
            {
                switch (command[0])
                {
                    case "add":
                        {
                            var index = int.Parse(command[1]);
                            var element = int.Parse(command[2]);
                            input.Insert(index, element);
                            break;
                        }
                    case "remove":
                        {
                            var index = int.Parse(command[1]);
                            input.RemoveAt(index);
                            break;
                        }
                    case "contains":
                        {
                            var element = int.Parse(command[1]);
                            int index = input.FindIndex(a => a == element);
                            Console.WriteLine(index);
                            break;
                        }
                    case "sumPairs":
                        {
                            for (int i = 0; i < input.Count; i++)
                            {
                                input[i] += input[i + 1];
                                input.RemoveAt(i + 1);
                            }
                            break;
                        }
                    case "shift":
                        {
                            var positions = int.Parse(command[1]);
                            RotateLeft(input, positions);
                            break;
                        }
                    case "addMany":
                        {
                            var pos = int.Parse(command[1]);
                            if (pos > input.Count)
                            {
                                break;
                            }
                            for (int i = command.Count - 1; i >= 2; i--)
                            {
                                input.Insert(pos, (int.Parse)(command[i]));
                            }
                            break;
                        }
                }
                command = Console.ReadLine().Split(' ').ToList();
            }

            Console.WriteLine($"[{string.Join(", ", input)}]");
        }
        public static void RotateLeftOnce(List<int> input)
        {
            var numToSwitch = input[0];
            for (var i = 0; i < input.Count; i += 1)
            {
                if (i + 1 < input.Count)
                {
                    var switcher = input[i];
                    input[i] = input[i + 1];
                    input[i + 1] = switcher;
                }
            }
        }
        public static void RotateLeft(List<int> input, int positions)
        {
            for (var i = 0; i < positions; i += 1)
            {
                RotateLeftOnce(input);
            }
        }
    }
}