[error] DEADLOCK/NODUP: no remaining values
        ???????
      +--------
E4BEE | 827E828
       -E4BEE
        =====
        EAA9E2
       -529935
        ======
         1924B8
        -A2006C
         ======
         ??????

base: 15
letters: 0123456789ABCDE
difficulty: medium
hints: 3 << 6, 8 << C, D << 0
missing: D