????????
      +---------
QXPTG | XHCCTCTT
       -PWPPX
        =====
        QQQQGC
       - WTTWG
        ======
         QGGYYT
        -QQCYLP
         ======
           XWXPT
          -XCWGT
           =====
           ?????

base: 10
letters: CGHLPQTWXY
difficulty: intermediate