????????
      +---------
MFQLW | HMXFMFRW
       -UWEHF
        =====
         QULUF
        -PELTU
         =====
          QTUNR
         -PELTU
          =====
           HWNWW
          -UWEHF
           =====
           ?????

base: 13
letters: EFHLMNPQRTUWX
difficulty: hard