HJY
      +--------
THTFJ | NQUXYPW
       -NTXJG
        =====
         FTGHP
        -UGPXH
         =====
          RTGJW
         -YURRL
          =====
           UQRG

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard
hints: X << G, H << P
missing: M