b-u bbb bbd bbi bbr bbu bdb bdd bdi bdr bdu bi- bib bid bii bir biu brb brd bri brr bru bub bud bui bur buu dbb dbd dbi dbr dbu ddb ddd ddi ddr ddu di- dib did dii dir diu drb drd dri drr dru dub dud dui dur i-d ibb ibd ibi ibr ibu idb idd idi idr idu iib iid iii iir iiu ir- irb ird iri irr iru iu- iub iud iui iur rbb rbd rbi rbr rbu rdb rdd rdi rdr rdu rib rid rii rir rrb rrd rri rrr rru rub rud rui rur ruu ubb ubi ubr ubu udb udd udi udr udu uib uid uii uir uiu ur- urb urd uri urr uru uur uuu