FTP
      +--------
WPMUL | TQYMXXG
       -TFXMN
        =====
         UHLPX
        -XUQYU
         =====
         WTWWQG
        -WJFHHJ
         ======
           QWQF

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard
hints: J << R
missing: R