????????
      +---------
THWQQ | LMWNJHFW
       -THWQQ
        =====
        GFQNUH
       -GYYHQF
        ======
         WJGTGF
        -WPPFQY
         ======
          GHLPWW
         -GYYHQF
          ======
          ??????

base: 13
letters: FGHJLMNPQTUWY
difficulty: intermediate