PRXJ
      +---------
JUPYG | QVTXJZVU
       -VPLQX
        =====
        JHXTVZ
       -JPNVWH
        ======
         PWUXWV
        -PQRPNM
         ======
           WQQZU
          -QWMMP
           =====
            ZPVV

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard