[error] DEADLOCK/NODUP: no remaining values
            F521
      +---------
F15CD | 7C4EB1F8
       -1F3BC
        =====
        CE9A41
       -C5895A
        ======
         C3D2FF
        -C9284D
         ======
          C51888
         -C2946C
          ======
           F6AF1

base: 16
letters: 0123456789ABCDEF
difficulty: challenging
missing: 0