bbbb bbbs bbox bobb bobo bobs boob boos boot boox boso boss bost botb boto bots bott bsos bsts btob btss bttb obbo obos obot obox obss obst obts oooo ooos oost ootb oots osoo osos ossb osso osts otbs oto- otoo otos otso otto otts oxo- oxos oxox oxxo s-os sbbs sbot sbst sobo sobs sobt soos soot soso soss sost soto sots soxs ssot sssb ssss sstb ssts stbs stob stoo stos stot stox stss tbbs tbox tbst tobo tobs tobt toos toot tosb toso toss tost tosx toto tots tott tox- toxo toxs toxt tsob tsos tsst tsts ttbb ttss tttt xbox xoxo xtbs xxxo xxxx