????????
      +---------
UPNXL | YYUXMPPL
       -UPNXL
        =====
        WFJHUP
       -WLUJUY
        ======
         WWUXYP
        -WLUJUY
         ======
          PHULYL
         - XFWEM
          ======
          ??????

base: 13
letters: EFHJLMNPQUWXY
difficulty: medium
missing: Q