???????
      +--------
YQTMR | PWPJTRT
       -YQTMR
        =====
        LWFFLR
       -WPQLJP
        ======
         YTEJQT
        -YGTGLY
         ======
         ??????

base: 13
letters: EFGJLMPQRTWXY
difficulty: challenging
missing: X