????????
      +---------
TRFLP | WRTFXRUW
       -TRFLP
        =====
        JYUGLR
       -JNLRQM
        ======
         JFPLPU
        -JLWFNX
         ======
          RXGXHW
         -RJUGLW
          ======
          ??????

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: medium