????????
      +---------
RTCCR | XUXUQFET
       -RTCCR
        =====
        EUGQRF
       -EEETTE
        ======
         CQQRUE
        -GFGCCF
         ======
          QXQQGT
         -QUQCCU
          ======
          ??????

base: 9
letters: CEFGQRTUX
difficulty: intermediate