a-a a-b a-c aaa aab aac aae aau ab- aba abb abc abe abu ac- aca acb acc ace acu aea aeb aec aee aeu au- aua aub auc aue b-u baa bab bac bae bau bba bbb bbc bbe bbu bca bcb bcc bce bcu be- bea beb bec bee beu bua bub buc bue buu c-- caa cab cac cae cau cba cbb cbc cbe cbu cca ccb ccc cce ccu ce- cea ceb cec cee ceu cua cub cuc cue cuu eaa eab eac eae eau eba ebb ebc ebe ebu ec- eca ecb ecc ece ecu eea eeb eec eee eu- eua eub euc eue ua- uaa uab uac uae uau uba ubb ubc ube ubu uca ucb ucc uce ucu uea ueb uec uee uua uuc uue uuu