aqcu qacu acqu caqu qcau cqau aquc qauc auqc uaqc quac uqac acuq cauq aucq uacq cuaq ucaq qcua cqua quca uqca cuqa ucqa
Note: these 'words' (valid or invalid) are all the permutations of the word aqcu. These words are obtained by scrambling the letters in aqcu.