LWN
     +-------
RRFL | LYMNYP
      -LXJP
       ====
        NNJY
       -WUTR
        ====
         FMQP
        -FHRX
         ====
          MFR

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard
hints: J << W << M, L << P
missing: G