????????
      ----------
QXQRF ) FPRNXECR
       -FXRNC
        =====
         YCCQE
        -YQXXQ
         =====
          PCQRC
         -PQQRR
          =====
           PXXER
          -YQXXQ
           =====
           ?????

base: 10
symbols: CEFNPQRWXY
missing: W
difficulty: medium