[error] DEADLOCK/NODUP: no remaining values
        ????????
      +---------
10EC9 | EB0E3332
       -10EC9
        =====
        732553
       -721357
        ======
         5A2813
        -590D3B
         ======
          6794C2
         -721357
          ======
          ??????

base: 15
letters: 0123456789ABCDE
difficulty: hard