[error] DEADLOCK/NODUP: no remaining values
        ????????
      +---------
85056 | 51003604
       -85056
        =====
        115006
       -355174
        ======
         424530
        -185207
         ======
          467454
         -417701
          ======
          ??????

base: 9
letters: 012345678
difficulty: medium