????????
      +---------
FYWMG | JEJGJWHN
       -FYWMG
        =====
         GPLQW
        -FYWMG
         =====
         MWQRGH
        -MRJWPQ
         ======
          MEJGLN
         -HGLNFP
          ======
          ??????

base: 13
letters: EFGHJLMNPQRWY
difficulty: medium