????????
      +---------
68A51 | AD8064CC
       -68A51
        =====
        3C5C44
       -398602
        ======
         38228C
        -34B27A
         ======
          3B9C2C
         -3D8C29
          ======
          ??????

base: 14
letters: 0123456789ABCD
difficulty: medium