????????
      +---------
PZYVG | XZGWYPZT
       -PZYVG
        =====
        QNHNWP
       - MXWJH
        ======
         UQRHGZ
        -QGNGPZ
         ======
          ZXGWNT
         -ZXHQHU
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: medium
hints: G << T
missing: L