????????
      +---------
PQRPP | PJUQTCEU
       -CGTCYW
        ======
         QCCEQE
        -QRGQWG
         ======
          CRYJPU
         -GCPCRJ
          ======
          ??????

base: 12
letters: CEFGJPQRTUWY
missing: F
difficulty: challenging