????????
      +---------
RQUUZ | UVHVRXZG
       -RQUUZ
        =====
         QJRYX
        -YTTPM
         =====
          HWTXZ
         -WVVHM
          =====
          XLWYZG
         -XNQUVZ
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard
hints: Y << N