nnrr nnrr nrnr rnnr nrnr rnnr nnrr nnrr nrnr rnnr nrnr rnnr nrrn rnrn nrrn rnrn rrnn rrnn nrrn rnrn nrrn rnrn rrnn rrnn
Note: these 'words' (valid or invalid) are all the permutations of the word nnrr. These words are obtained by scrambling the letters in nnrr.