???????
      +--------
FWQNJ | HGWFGXW
       -FWQNJ
        =====
        WRFQHX
       -WNWXTW
        ======
         FYQMQW
        -WXTRYG
         ======
         ??????

base: 13
letters: FGHJLMNQRTWXY
difficulty: medium
missing: L