LNF
      +--------
PMGFF | HPRPTGL
       -GHXFJ
        =====
        LYPPYG
       -LRGUFT
        ======
         PHTNWL
        -PYHTFW
         ======
          WULLW

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