GFY
      +--------
MNHYM | LGHFFXL
       -NHGQJ
        =====
        GQMNNX
       -GRQWLU
        ======
         RNPYXL
        -RQRUXU
         ======
          TLYUL

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