NFTL
      +---------
JQYFH | THQWPWXR
       -JQYFH
        =====
        JPLPYW
       -JTWPHR
        ======
         NGFUUX
        -NQYYRH
         ======
          NRPXGR
         -NTTFQM
          ======
           JNJNR

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: medium