XYY
     +-------
HYQY | PWGPJJ
      -GGYN
       ====
       HPLMJ
      -HGHWJ
       =====
        HPXRJ
       -HGHWJ
        =====
         HHHR

base: 13
letters: GHJLMNPQRUWXY
difficulty: hard
missing: U