???????
      +--------
QMLQX | MWYQLTR
       -QMLQX
        =====
        FTLJJT
       -FWFYWJ
        ======
         FPTLQR
        -FPNQPL
         ======
         ??????

base: 13
letters: EFJLMNPQRTWXY
difficulty: hard
hints: F << E
missing: E