FWNX
      ----------
 XNXX ) FWUAYTWY
       -TXEXW
        =====
         WNAFT
        -EXTXF
         =====
          NNFXW
         -WXAXT
          =====
           XTYUY
          -NXYXA
           =====
            TXUX

base: 10
symbols: ACEFNTUWXY
difficulty: intermediate
missing: C