???????
      +--------
QJYXJ | GWQUFTJ
       -QJYXJ
        =====
        QYXHLT
       -XPFHYM
        ======
         YGNJGJ
        -YUPQTP
         ======
         ??????

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard
missing: R