?????????
      +----------
HJQPG | YPPVMXLMT
       -HJQPG
        =====
        HHPXJX
       -HHNRNX
        ======
          GYNUL
         -VVTPQ
          =====
           ZVWRM
          -XTMRZ
           =====
            GMQTT
           -GMTHV
            =====
            ?????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: medium