oooo ooos oops oort oost ootp oots opo- opor opos oppo opps opqr opto opts oro- oror oros orot orps orro orrs orso orto orts osoo osor osos osro osso ostr osts oto- otoo otor otos otpp otro otrs otso otto otts poop poor poos poot pop- popo popp pops popt poro porr pors port poso poss post poto pots pott ppos pppo pppp ppps ppss ppts pptt pqrs pro- proo prop pros prot prps prrs prso prss prtp prtr psos pspp pspr psps psrp psso psst psts ptop qoop qqqq qrss qrst qsos qsqs qsqt qsrs qtos qtrs roop roor roos root ropo rops roro rort roso rosp ross rost roto rotr rots rott rpos rpps rpts rrrr rrsp rsos rspo rsps rstp rsts rtps rtss rttp rtts s-os soop soor soos soot sopo sopp sops soro sorr sors sort soso soss sost soto sotp sots spoo spop spor spos spot spps spqr spro sprs spso spsp spss spst spto sptr spts sqrt sros srps srpt srsp srtp srtr ssop ssot sspo ssps sspt ssrs ssss sstp ssts stoo stop stor stos stot stpp stps stro strs stss sttr toor toos toot top- topo topp tops topt toro torp torq torr tors tort toso toss tost toto totr tots tott tppp tppr tprs tptp tptr troo trop tros trot trpp trps trst trtr tsop tsos tspo tsps tspt tssr tsst tsts ttop ttss tttt