????????
      +---------
QYRYL | YCUCFQYY
       -FPYPC
        =====
        QYRYRQ
       -QFQRMQ
        ======
         QYRYPY
        -QFQRMQ
         ======
          QYCRFY
         -QFQRMQ
          ======
          ??????

base: 10
letters: CFLMPQRUWY
difficulty: medium
missing: W