LJVV
      +---------
GYRGJ | RPWHYJJU
       -GYRGJ
        =====
        LHJTQJ
       -LLWPNU
        ======
         PPRZYJ
        -PNXYVJ
         ======
          PMWPNU
         -PNXYVJ
          ======
           MVMHJ

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard