????????
      +---------
PWYJR | TLPHRHYL
       -PWYJR
        =====
        WXPXEH
       -WGYXTG
        ======
         HPYRRY
        -HPMFXJ
         ======
           FEYGL
          -JPLYT
           =====
           ?????

base: 14
letters: EFGHJLMPRTUWXY
difficulty: hard
missing: U