????????
      +---------
PHQPN | NLEQMLNR
       -PHQPN
        =====
         QNGRL
        -RGMGM
         =====
          GQXNN
         -YNPTR
          =====
          LTUQGR
         -LHNUNQ
          ======
          ??????

base: 14
letters: EFGHLMNPQRTUXY
difficulty: medium
missing: F