YTU
      +--------
YYXWL | GJXURYN
       -WLFNU
        =====
        YYQYHY
       -YPFJPU
        ======
         HNUPJN
        -HGMYML
         ======
          HRXFQ

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