TJXZ
      +---------
QJVMG | YXJXURGY
       -QJVMG
        =====
        NMRJMR
       -UGPQVL
        ======
         LTPYZG
        -JRZNHY
         ======
          MMQZUY
         -MTLXUU
          ======
           NURHX

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