Help with regexp

I am stack with this challenge:
[Regex Golf](https://this challenge)
I was able to capture 2 char mirroring with this expression: (\w{1})(\w{1})\2\ but could not to exclude any word that contains such pattern while keeping any word that does not. Any help will be appreciated

what issue are you having? all the words you want to match contain foo and those you don’t want to match don’t

With help from friends this is the solution:
^(?!\w*(\w)(\w)\2\1)

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