????????
      +---------
283DC | 9BD8C4C9
       -283DC
        =====
        D84164
       -D46AC9
        ======
         22823C
        -26C940
         ======
          DCA0D9
         -D8057D
          ======
          ??????

base: 14
letters: 0123456789ABCD
difficulty: hard