???????
      +--------
QPGGL | HWPQFMR
       -RWYTQ
        =====
        WFQGHM
       -WTNXWG
        ======
          FGMWR
         -HNQQT
          =====
          ?????

base: 13
letters: FGHLMNPQRTWXY
difficulty: hard
hints: M << L