????????
      +---------
MUMJJ | MHNTLJHR
       -MUMJJ
        =====
         QQNQJ
        -FPFWW
         =====
          UMQGH
         -RHRWY
          =====
           UPGTR
          -RHRWY
           =====
           ?????

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard
hints: U << J
missing: X