XLVG
      +---------
JTMQW | TGLLPLYJ
       -JTMQW
        =====
        PUPRYL
       -PZNJNL
        ======
         PQLNRY
        -PUHYPX
         ======
           LTVVJ
          -MXPZU
           =====
           PNUZU

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: medium