????????
      +---------
2032B | CB44770C
       -2032B
        =====
        3CC737
       -3266B8
        ======
         368CA0
        -3266B8
         ======
          1CA26C
         -109BB2
          ======
          ??????

base: 13
letters: 0123456789ABC
difficulty: hard
missing: 5