bbb bbi bbn bbs bbx bi- bib bii bin bis bix bnb bni bnn bns bnx bsb bsi bsn bss bsx bxb bxi bxn bxx ibb ibi ibn ibs ibx iib iii iin iis iix in- inb ini inn ins inx is- isb isi isn iss ixi ixn n-i nbb nbi nbn nbs nbx nib nii nin nis nix nnb nni nnn nns nsb nsi nsn nss nsx sbb sbi sbn sbs sbx sib sii sin sis six snb sni snn sns ss- ssb ssi ssn sss ssx sxi sxn sxs xbx xii xin xis xix xns xsb xsi xss xxi xxx