LQG
      +--------
FRNHL | RJFGPTU
       -QGQPY
        =====
        FXNYNT
       -FYJJQW
        ======
         YGXHQU
        -YGFPWF
         ======
           YYJX

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: challenging
missing: M