04. Array Matcher

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {

        string[] inputAsArray = Console.ReadLine().Split('\\');
        string leftChars = inputAsArray[0];
        string rightChars = inputAsArray[1];
        string command = inputAsArray[2];

        string[] leftCharsArray = new string[leftChars.Length];

        for (int i = 0; i < leftChars.Length; i++)
        {
            leftCharsArray[i] = Convert.ToString(leftChars[i]);
        }

        List<string> leftCharsList = new List<string>();

        for (int i = 0; i < leftCharsArray.Length; i++)
        {
            leftCharsList.Add(leftCharsArray[i]);
        }


        string[] rightCharsArray = new string[rightChars.Length];

        for (int i = 0; i < rightChars.Length; i++)
        {
            rightCharsArray[i] = Convert.ToString(rightChars[i]);
        }
            List<string> rightCharsList = new List<string>();

        for (int i = 0; i < rightCharsArray.Length; i++)
        {
            rightCharsList.Add(rightCharsArray[i]);
        }

        List<string> outPut = new List<string>();

        switch (command)
        {
            case "join":
                foreach (var letter in leftCharsList)
                {
                    if (rightCharsList.Contains(letter))
                    {
                        outPut.Add(letter);
                    }
                }
                break;
            case "right exclude":
                foreach (var letter in leftCharsList)
                {
                    if (rightCharsList.Contains(letter))
                    {
                        continue;
                    }
                    else
                    {
                        outPut.Add(letter);
                    }
                }
                break;
            case "left exclude":
                foreach (var letter in rightCharsList)
                {
                    if (leftCharsList.Contains(letter))
                    {
                        continue;
                    }
                    else
                    {
                        outPut.Add(letter);

                    }
                }
                break;
        }
        outPut.Sort();

        string output = "";
        foreach (var item in outPut)
        {
            output = output + item;
        }

        Console.WriteLine(output);
        }
    }