JXF
      +---------
LYMWX | MYRRTHGF
       -GTMRGG
        ======
         UYHQTG
        -YQRLJJ
         ======
          RUMLFF
         -RGWTTL
          ======
           WQLTJ

base: 13
letters: FGHJLMQRTUWXY
difficulty: intermediate
restrictions: no multiplication