[error] DEADLOCK/NODUP: no remaining values
        ????????
      +---------
084A8 | 1A2B8590
       -084A8
        =====
        52A635
       -56A057
        ======
         53B669
        - 084A8
         ======
          A1A470
         -AAB942
          ======
          ??????

base: 12
letters: 0123456789AB
difficulty: intermediate