???????
      +--------
XLQRH | QMLLFMU
       -XLQRH
        =====
        LNLFHM
       - XLQRH
        ======
         LQUEYU
        -LJEQNF
         ======
         ??????

base: 13
letters: EFGHJLMNQRUXY
difficulty: hard
attributes: great zero indirection
missing: G