a-a a-b a-c a-t aaa aab aac aat aau ab- aba abb abc abt abu ac- aca acb acc act acu at- ata atb atc att atu au- aua aub auc aut b-u baa bab bac bat bau bba bbb bbc bbt bbu bca bcb bcc bct bcu bta btb btc btt btu bua bub buc but buu c-- caa cab cac cat cau cba cbb cbc cbt cbu cca ccb ccc cct ccu cta ctb ctc ctt ctu cua cub cuc cut cuu taa tab tac tat tau tba tbb tbc tbt tbu tca tcb tcc tct tcu tta ttb ttc ttt ttu tua tub tuc tut tuu ua- uaa uab uac uat uau uba ubb ubc ubt ubu uca ucb ucc uct ucu uta utb utc utt utu uua uuc uut uuu