GZJZ
      +---------
NNRNL | YTUVZQYJ
       -NNRNL
        =====
        TWJGRQ
       -TZXQPR
        ======
         TJVQXY
        -TVZLQL
         ======
          TQWMJJ
         -TZXQPR
          ======
            WHHW

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard
missing: H