HWQX
      ----------
 XQXX ) HWTFCNWC
       -NXYXW
        =====
         WQFHN
        -YXNXH
         =====
          QQHXW
         -WXFXN
          =====
           XNCTC
          -QXCXF
           =====
            NXTX

base: 10
symbols: ACFHNQTWXY
difficulty: intermediate
missing: A