????????
      +---------
XZGUZ | UGXNPGLW
       -XZGUZ
        =====
        XGWGGG
       -XGQNTG
        ======
          UTVYL
         -XZGUZ
          =====
          XWPWZW
         -XTMNRJ
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard
hints: J << T, U << M
missing: H