????????
      +---------
JTHFH | MRPRJRNT
       -HHPNQ
        =====
         XUJHR
        -QPTWF
         =====
         NNMNQN
        -NUYNQX
         ======
           QXXJT
          -QPTWF
           =====
           ?????

base: 13
letters: FHJMNPQRTUWXY
difficulty: intermediate