a-a a-b a-t aaa aab aak aao aar aat aau ab- aba abb abk abo abr abt abu aka akb akk ako akr aku aoa aob aok aoo aor aot aou ar- ara arb ark aro arr art aru at- ata atb ato atr att atu au- aua aub auk auo aur aut b-u baa bab bak bao bar bat bau bba bbb bbk bbo bbr bbt bbu bka bkb bkk bko bkr bkt boa bob bok boo bor bot bou bra brb brk bro brr brt bru bta btb btk bto btr btt btu bua bub buk buo bur but buu k-t ka- kaa kab kak kao kar kat kau kba kbb kbk kbo kbr kbu kkb kkk kkr kkt kku koa kob kok koo kor kot kou kra krk kro krr krt kru kta ktb ktk kto ktr ktt ktu kub kuk kur kut kuu oaa oab oak oao oar oat oau ob- oba obb obk obo obr obt obu oka okb okk oko okr oku oo- ooa oob ook ooo oor oot or- ora orb ork oro orr ort oru ot- ota otb otk oto otr ott otu ou- oua ouk ouo our out ra- raa rab rak rao rar rat rau rba rbb rbk rbo rbr rbt rbu rkb rkk rko rkt rku roa rob rok roo ror rot rou rra rrb rrk rrr rrt rru rta rtb rtk rto rtr rtt rtu rua rub ruk ruo rur rut ruu taa tab tak tao tar tat tau tba tbb tbk tbo tbr tbt tbu tka tkb tkk tko tkr tkt to- toa tob tok too tor tot tou tra trb trk tro trr trt tru tta ttb ttk tto ttr ttt ttu tua tub tuk tuo tur tut tuu ua- uaa uab uak uao uar uat uau uba ubb ubk ubo ubr ubt ubu uka ukb ukk ukr uku uoa uob uok uoo uor uot ur- ura urb urk uro urr urt uru uta utb utk uto utr utt utu uua uur uut uuu