????????
      +---------
LQXHF | QUHFJFHU
       -JFXEY
        =====
        LLMRQF
       -LXUMRL
        ======
          EQRHH
         -PNQMP
          =====
           HHXPU
          -MYLRN
           =====
           ?????
base: 13
letters: EFHJLMNPQRUXY
difficulty: hard