obkc bokc okbc kobc bkoc kboc obck bock ocbk cobk bcok cbok okcb kocb ockb cokb kcob ckob bkco kbco bcko cbko kcbo ckbo
Note: these 'words' (valid or invalid) are all the permutations of the word obkc. These words are obtained by scrambling the letters in obkc.