????????
      +---------
YLQUX | JRHMZWZH
       -YLQUX
        =====
        MJNLYW
       -MMVGXU
        ======
         XTPMJZ
        -XVZUGV
         ======
          YXVJGH
         -YNHNHQ
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: medium