LFU
      +--------
PFJQN | YWXTJNW
       -PFJQN
        =====
        LJYMGN
       -LFHRNF
        ======
         LNXQWW
        -LGQWGT
         ======
          LTUQG

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard
missing: U