RJJ
      +--------
PWGLP | UFGWJRF
       -QXFPR
        =====
        PFLRYR
       -PLQTTJ
        ======
         PFXHNF
        -PLQTTJ
         ======
          PLYFR

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