????????
      +---------
NJTUR | HLNRYNNY
       -NJTUR
        =====
        UMUZTN
       -YPQVUM
        ======
         XHLYQN
        -XQYZJN
         ======
          XPNZWY
         -XQYZJN
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard
hints: Y << T, Y << N, M << N
missing: G