XQM
      +--------
UPHFN | MJGJQNU
       -TUFMN
        =====
        ULRHXN
       -UURMRR
        ======
         URLXNU
        - GJYUH
         ======
           FTJW

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