????????
      +---------
WLXYR | NRPQLLUN
       -WLXYR
        =====
         LJRXL
        -WLXYR
         =====
         MXUUXU
        -MJYRMR
         ======
          XPFURN
         -XXRPLU
          ======
          ??????

base: 12
letters: FJLMNPQRUWXY
difficulty: hard