????????
      +---------
YLWHF | YTGPLHUQ
       -YLWHF
        =====
         HQWWH
        -YLWHF
         =====
         PHMYGU
        -PPRFUP
         ======
          PQLRHQ
         -PWPYHW
          ======
          ??????

base: 13
letters: FGHJLMPQRTUWY
difficulty: hard
hints: R << Y
missing: J