rrsb rrsb rsrb srrb rsrb srrb rrbs rrbs rbrs brrs rbrs brrs rsbr srbr rbsr brsr sbrr bsrr rsbr srbr rbsr brsr sbrr bsrr
Note: these 'words' (valid or invalid) are all the permutations of the word rrsb. These words are obtained by scrambling the letters in rrsb.