pfe[8], efo[7], che[6], ech[6], hec[6], hoc[6], och[6], hep[6], hop[6], cep[5], pop[5],
ef[6], fe[6], eh[4], he[4], ho[4], oh[4], ce[3], co[3], pe[3], op[3], po[3], eo[2],
