UGR
      +--------
UWXPW | GUJTJNU
       -YPWJM
        =====
        TJRMWN
       -TYFJFM
        ======
         TRHWUU
        -TGXQNJ
         ======
           YGYN

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