????????
      +---------
VUWZU | HGUVZXUZ
       -VUWZU
        =====
         WRUJX
        -VUWZU
         =====
         GHRHYU
        -GTPNQU
         ======
          GRXMRZ
         -TLYLLR
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard