HPX
      +--------
HWTWJ | XHFXNNG
       -YJWXM
        =====
        GNTMPN
       -GTTPRH
        ======
         GLWWRG
        - FXNQU
         ======
          GPRHY

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard