JGHM
      +---------
JVMZG | XQLUVWXH
       -JVMZG
        =====
        JVRLRW
       -JLURPJ
        ======
         JZHQXX
        -JYYMMU
         ======
          JPYPJH
         -JQMTWX
          ======
            VQMR

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard
missing: N