????????
      +---------
RHNJX | PGMTNHGL
       -HRJWG
        =====
        JWJHJH
       - FFHUW
        ======
         RMLXQG
        -RYRYGN
         ======
          MPPFLL
         -MGJRFF
          ======
          ??????

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard