????????
      +---------
WXGFL | JPGXNLTT
       -WXGFL
        =====
        MFQUPL
       -MFJMQM
        ======
          PFUMT
         -FWFNP
          =====
          MWMWQT
         -MYXGYP
          ======
          ??????

base: 14
letters: FGJLMNPQRTUWXY
difficulty: medium
missing: R