using System;

using System.Collections.Generic;

using System.Text.RegularExpressions;

public class Program

{

​

    public static void Main()

    {

        Console.WriteLine("..starting");

        string sentence = "Lorem ipsum left right sit amet, consectetur adipiscing elit, sed do  eiusmod tempor incididunt ut labore et dolore  magna aliqua.";

        Regex regexLeft = new Regex("\\bleft\\b", RegexOptions.IgnoreCase);

        Regex regexRight = new Regex("\\bright\\b", RegexOptions.IgnoreCase);

        Regex regexBoth = new Regex("\\bboth|multifocal|bilateral\\b", RegexOptions.IgnoreCase);

        Match BothMatch = regexBoth.Match(sentence);

        Match LeftMatch = regexLeft.Match(sentence);

        Match RightMatch = regexRight.Match(sentence);

        if (BothMatch.Success)

        {

            Console.WriteLine("BOTH keyword match '" + BothMatch.Value + "' found at char " + BothMatch.Index);

        }

        else if(!((LeftMatch.Success || RightMatch.Success) && !(LeftMatch.Success && RightMatch.Success)))

        {

            Console.WriteLine("Match 1 LEFT match: '" + LeftMatch.Value + "' found at char " + LeftMatch.Index + " ... " + "RIGHT match: '" + RightMatch.Value + "' found at char " + RightMatch.Index);

        }

        else if(LeftMatch.Success && RightMatch.Success)

        {

            Console.WriteLine("Match 2 LEFT match: '" + LeftMatch.Value + "' found at char " + LeftMatch.Index + " ... " + "RIGHT match: '" + RightMatch.Value + "' found at char " + RightMatch.Index);

        }

        else{

            Console.WriteLine("There was no match");

        }

    }

}