????????
      +---------
QWLNL | GUGNMRLH
       -HMPXP
        =====
        PGYWNR
       -PYYLNH
        ======
         PULTNL
        -PXWPRU
         ======
          PNXWRH
         -PPGNLQ
          ======
          ??????

base: 13
letters: GHLMNPQRTUWXY
difficulty: medium