using System;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
 
 
String s = @"
Console.WriteLine(""FOUND line without""); // anything.
Console.WriteLine(""FOUND line without""); // ALLOWEDTAG
Console.WriteLine(""FOUND line without""); // something else.
Console.WriteLine(""FOUND line without""); // ALLOWEDTAG
";
 
foreach (Match m in Regex.Matches(s, @"(?m)^(?!.*ALLOWEDTAG).*WriteLine.*$"))
         Console.WriteLine(m.Value); 
 
 
	}
}

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