????????
      +---------
PNFQH | HQYYGXUJ
       -GJTQR
        =====
        NGWRXX
       -NLWHMR
        ======
         FQUNTU
        -FURMHH
         ======
          FXFRQJ
         -NUFXML
          ======
          ??????

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard