how to make this regex insensitive

how to make this regex insensitive

I have been working with regex lately and this following code filters out 2 words perfectly but I can seem to make it case-insensitive
  1.  [RegularExpression("^((?!(Stupid|www)).)*$", ErrorMessage = "Invalid character")]
That above filters out 2 words but if a user writes Www then it gets pass the regex, how can I correct that I have heard that maybe ?i will work but do not know where to put it in there; i'm new to this any help would be great.