????????
      +---------
FUCPF | UCMXRXWU
       -YMLNY
        =====
         PWFYX
        -PUPNN
         =====
          UYMFW
         -YMLNY
          =====
           WMCCU
          -MCCYC
           =====
           ?????

base: 12
letters: CEFLMNPRUWXY
difficulty: medium
attributes: good demo
missing: E