bum[8], umb[8], but[8], tub[8], bun[7], bru[7], bur[7], tum[7], mun[6], mru[6], mur[6], rum[6], nut[6], rut[6], tur[6], nur[5], run[5], urn[5],
bu[6], mu[5], tu[5], ut[5], nu[4],