ZHMG
      +---------
ZWGGV | YNYPJPQU
       -ZWGGV
        =====
        ZRQTWP
       -ZURXXY
        ======
          WRTMQ
         -THPPT
          =====
          ZJLWTU
         -ZPNZZX
          ======
           ZJJPN

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: medium