PXJ
      +--------
PXGLW | HTGMJYY
       -YFPQJ
        =====
        GTFPUY
       -GPYJNJ
        ======
         GJXYNY
        -GXTWXT
         ======
          PTXTG

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