????????
      +---------
ETMYW | XYPXPRRY
       -ETMYW
        =====
         PPTXR
        -WUTGN
         =====
         EFMFWR
        -ENXNWY
         ======
          EUEQPY
         -EUQYTU
          ======
          ??????

base: 13
letters: EFGMNPQRTUWXY
difficulty: hard