opeer[6], opero[6], reper[6], peror[6],
oper[5], pero[5], poro[5], ropo[5], oere[4], oreo[4],
per[4], rep[4], por[4], pro[4], rop[4], prr[4], ero[3], oro[3],
pe[3], op[3], po[3], ee[2], eo[2], er[2], re[2], or[2], ro[2],
