????????
      +---------
MUJNU | UUJHRLQT
       -XPWRP
        =====
        GXHGRL
       -GJQQWP
        ======
         QXYYLQ
        -QZWLRU
         ======
          GQLJHT
         -GGRNYU
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard
hints: Z << N, J << T
missing: V