???????
      +--------
RXQRJ | GNLTJUW
       -YMTNT
        =====
        JMVLYU
       -JTJLVM
        ======
         VJPZVW
        -JGVVZQ
         ======
         ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard
hints: Q << W, Z << H
missing: H