????????
      ----------
MCFXX ) CUPXCFUU
       -MCFXX
        =====
        QFUTPF
       -QUQMFF
        ======
         XPMUTU
        -XQXTGC
         ======
          XHMHWU
         -XQXTGC
          ======
          ??????

base: 11
symbols: CFGHMPQTUWX
difficulty: medium