????????
      +---------
LWQHR | ULMMWURZ
       -LWQHR
        =====
        XRYWMU
       -JVQRPW
        ======
         HWLVQR
        -RVHVNG
         ======
          GWTNZZ
         -WPZZLZ
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard