????????
      +---------
PQRJT | GHRPXFRJ
       -PQRJT
        =====
        RTMYGF
       -RXUHPY
        ======
         YWQPYR
        -YQXUHQ
         ======
          JWFHXJ
         -JNTGUN
          ======
          ??????

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard
hints: H << L
missing: L