NGQZ
      +---------
JGHMZ | ZJWZURMY
       -JGHMZ
        =====
        NXYNVR
       -NVZVPZ
        ======
         NQGQXM
        -NGPTLX
         ======
           URVUY
          -QWXPL
           =====
           NHTTY

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: medium