LGG
      +---------
LWNUL | JXXMJXTF
       -JNXFMW
        ======
         YWUFTT
        -YXUMEN
         ======
          FPYFGF
         -YXUMEN
          ======
           FGMXT

base: 13
letters: EFGJLMNPTUWXY
difficulty: medium
restrictions: no multiplication