ArrayManipulator

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

namespace ArrayManipulator
{
    class Program
    {
        static void Main()
        {
            List<int> inputList = Console.ReadLine().Split().Select(int.Parse).ToList();

            while (true)
            {
                string[] tokens = Console.ReadLine().Split();

                string command = tokens[0];

                if (command == "print")
                    break;

                switch (command)
                {
                    case "add":
                        int index = int.Parse(tokens[1]);
                        int element = int.Parse(tokens[2]);
                        inputList.Insert(index, element);
                        break;

                    case "addMany":
                        index = int.Parse(tokens[1]);
                        List<int> elementsToAdd = new List<int>();
                        AddMany(inputList, tokens, index, elementsToAdd);
                        break;

                    case "contains":
                        element = int.Parse(tokens[1]);
                        ContainsPrintIndex(inputList, element);
                        break;

                    case "remove":
                        index = int.Parse(tokens[1]);
                        inputList.RemoveAt(index);
                        break;

                    case "shift":
                        int positions = int.Parse(tokens[1]);
                        ShiftList(inputList, positions);
                        break;

                    case "sumPairs":
                        SumPairs(inputList);
                        break;
                }
            }

            Console.WriteLine($"[{String.Join(", ", inputList)}]");
        }

        private static void SumPairs(List<int> inputList)
        {

            for (int i = 1; i < inputList.Count; i++)
            {
                int sumedPair = 0;
                sumedPair = inputList[i] + inputList[i - 1];
                inputList.Insert(i - 1, sumedPair);
                inputList.RemoveRange(i, 2);
            }
        }

        private static void ShiftList(List<int> inputList, int positions)
        {
            for (int i = 0; i < positions; i++)
            {
                inputList.Add(inputList[0]);
                inputList.RemoveAt(0);
            }
        }

        private static void ContainsPrintIndex(List<int> inputList, int element)
        {
            if (inputList.Contains(element))
            {
                for (int i = 0; i < inputList.Count; i++)
                {
                    if (inputList[i] == element)
                    {
                        Console.WriteLine(i);
                    }
                }
            }
            else
            {
                Console.WriteLine(-1);
            }
        }

        private static void AddMany(List<int> inputList, string[] tokens, int index, List<int> elementsToAdd)
        {
            for (int i = 2; i < tokens.Length; i++)
            {
                elementsToAdd.Add(int.Parse(tokens[i]));
            }

            inputList.InsertRange(index, elementsToAdd);
        }
    }
}