????????
      +---------
NRYXQ | FYGLHGRH
       -NRYXQ
        =====
        MTJNJG
       - NRYXQ
        ======
         NRYMUR
        -NUTFWM
         ======
          NRNWWH
         -NUTFWM
          ======
          ??????

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