a-a a-b a-c aaa aab aac aad aao aar aax ab- aba abb abc abd abo abr abx ac- aca acb acc acd aco acr acx ad- ada adb adc add ado adr adx aoa aob aoc aod aoo aor aox ar- ara arb arc ard aro arr arx ax- axa axo axr axx baa bab bac bad bao bar bax bba bbb bbc bbd bbo bbr bbx bca bcb bcc bcd bco bcr bcx bda bdb bdc bdd bdo bdr bdx boa bob boc bod boo bor box bra brb brd bro brr brx bxb bxd bxo bxx c-- caa cab cac cad cao car cax cba cbb cbc cbd cbo cbr cbx cca ccb ccc ccd cco ccr ccx cda cdb cdc cdd cdo cdr cdx co- coa cob coc cod coo cor cox cra crb crc crd cro crr crx cxc cxo cxr cxx daa dab dac dad dao dar dax dba dbb dbc dbd dbo dbr dbx dca dcb dcc dcd dco dcr dcx dda ddb ddc ddd ddo ddr ddx doa dob doc dod doo dor dox dra drb drc drd dro drr drx dxc dxd dxo dxr dxx oaa oab oac oad oao oar oax ob- oba obb obc obd obo obr obx oc- oca ocb occ ocd oco ocr ocx oda odb odc odd odo odr oo- ooa oob ooc ood ooo oor oox or- ora orb orc ord oro orr orx ox- oxa oxb oxc oxo oxx ra- raa rab rac rad rao rar rax rba rbb rbc rbd rbo rbr rbx rca rcb rcc rcd rco rcr rcx rda rdb rdc rdd rdo rdr rdx roa rob roc rod roo ror rox rra rrb rrc rrd rrr rxr xaa xac xad xar xbc xbr xbx xcb xcd xcr xcx xda xdb xdc xdr xoa xoc xod xoo xor xox xrc xrd xrx xxo xxx