YXLZ
      +---------
UJMTW | PYRQUWPM
       -LRZYQ
        =====
        NWNUZW
       -NHMXGP
        ======
         XGYNQP
        -XMLNPQ
         ======
          WJVPWM
         -WJHUQW
          ======
            VMPY

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard