UMJP
      +---------
RHGNY | GQZZHRXM
       -RHGNY
        =====
        UQXMMR
       -UPVGGP
        ======
         PVTJNX
        -PYTQVP
         ======
          NLUPQM
         -UJVLJL
          ======
           PMMVM

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