CodeWarsKata: Syntax Highlighting

CodeWarsKata_RoboScript1_SyntaxHighlighting.cs

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

namespace CodeWarsKata_RoboScript1_SyntaxHighlighting
{
    class Program
    {
        static void Main(string[] args)
        {
            string code = "FFFR(345)F2LL";
            Console.WriteLine(Highlight(code));
        }

        public static string Highlight(string code)
        {
            //F - <span style="color: pink">F</span>
            //L - <span style="color: red">L</span>
            //R - <span style="color: green">R</span>
            //0 => 9 - <span style="color: orange">#</span>
	    //() - Do not highlight, just add to answer string 

            foreach (var item in code)
            {
                Console.Write(item);
            }
            Console.WriteLine();

            string answer = "";

            for (int i = 0; i < code.Length; i++)
            {
                //F
                if (code.ElementAt(i) == 'F')
                {
                    answer += "<span style=\"color: pink\">F";
                    if (i != (code.Length - 1))
                    {
                        if (code.ElementAt(i + 1) == 'F' && i != (code.Length - 1))
                        {
                            while (i != (code.Length - 1) && code.ElementAt(i + 1) == 'F')
                            {
                                answer += "F";
                                i++;
                            }
                            answer += "</span>";
                        }
                        else answer += "</span>";
                    }
                    else answer += "</span>";
                }

                //L
                if (code.ElementAt(i) == 'L')
                {
                    answer += "<span style=\"color: red\">L";
                    if (i != (code.Length - 1))
                    {
                        if (code.ElementAt(i + 1) == 'L' && i != (code.Length - 1))
                        {
                            while (i != (code.Length - 1) && code.ElementAt(i + 1) == 'L')
                            {
                                answer += "L";
                                i++;
                            }
                            answer += "</span>";
                        }
                        else answer += "</span>"; 
                    }
                    else answer += "</span>";
                }

                //R
                if (code.ElementAt(i) == 'R')
                {
                    answer += "<span style=\"color: green\">R";
                    if (i != (code.Length - 1))
                    {
                        if (code.ElementAt(i + 1) == 'R')
                        {
                            while (i != (code.Length - 1) && code.ElementAt(i + 1) == 'R')
                            {
                                answer += "R";
                                i++;
                            }
                            answer += "</span>";
                        }
                        else answer += "</span>"; 
                    }
                    else answer += "</span>";
                }

                //0
                if (char.IsDigit(code.ElementAt(i)) == true)
                {
                    answer += $"<span style=\"color: orange\">{code.ElementAt(i)}";
                    if (i != (code.Length - 1))
                    {
                        if (char.IsDigit(code.ElementAt(i + 1)) == true && i != (code.Length - 1))
                        {
                            while (i != (code.Length - 1) && char.IsDigit(code.ElementAt(i + 1)) == true)
                            {
                                answer += code.ElementAt(i + 1);
                                i++;
                            }
                            answer += "</span>";
                        }
                        else answer += "</span>";
                    }
                    else answer += "</span>";
                }

                //()
                if (code.ElementAt(i) == '(' || code.ElementAt(i) == ')')
                {
                    answer += $"{code.ElementAt(i)}";
                }
            }
            Console.WriteLine(answer);
            Console.ReadKey();
            return answer;
        }
    }
}