????????
      +---------
QEMQH | EJMWJYWR
       -QEMQH
        =====
        QGXHHY
       -QQQYNE
        ======
          FXQMW
         -QEMQH
          =====
          HHYEQR
         -YRGXWF
          ======
          ??????

base: 13
letters: EFGHJLMNQRWXY
difficulty: hard
missing: L