93k21a a4k2 b4k21 c4k21a d4k2
yul2 zul21 0ul21a 1ul2 2ul21
nlm21 olm21a plm2 qlm21 rlm21a
ccn21a dcn2 ecn21 fcn21a gcn2
12n2 22n21 32n21a 42n2 52n21