????????
      +---------
PMTQP | JXFEWJJX
       -XUGPX
        =====
         XQHJJ
        -MWFXM
         =====
         PYGPTJ
        -PYWXHG
         ======
           PWFEX
          -PMTQP
           =====
           ?????

base: 13
letters: EFGHJMPQTUWXY
difficulty: hard