????????
      +---------
NMYPT | WQZLRWTU
       -NMYPT
        =====
         JJHPW
        -NMYPT
         =====
         ZVMVNT
        -HRVTZY
         ======
          HULVWU
         -HUUNMG
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: challenging
missing: X