using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
		var replacingValues = new Dictionary<string, string> { { "Crazy", "XXX" } };
        var test = "viv-ek is a good boy.Mah - esh is Cra - zy.";
        var replacedTest =
            Regex.Replace(
                test,
                @"\b(?<part>\w+)(\s*-\s*(?<part>\w+))+\b",
                match =>
                    {
                        var word = string.Join(string.Empty, match.Groups["part"].Captures.Cast<Capture>().SelectMany(capture => capture.Value));
                        string replacingValue;
                        return replacingValues.TryGetValue(word, out replacingValue) ? replacingValue : match.Value;
                    });
        Console.WriteLine(replacedTest);
	}
}

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