????????
      +---------
NQNTL | GHNHTGNP
       -NQNTL
        =====
        NNEPPG
       - YFMYH
        ======
         NPHPJN
        -NWPNNM
         ======
          NJWGWP
         -NGYHPT
          ======
          ??????

base: 13
letters: EFGHJLMNPQTWY
difficulty: intermediate