ZZWU
      +---------
QZZQR | QNMQNHVG
       -QZZQR
        =====
         RZYZH
        -QZZQR
         =====
          LUJMV
         -PWWPL
          =====
          WGXRGG
         -WTLZPN
          ======
           MVWLR

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: medium