?????????
      +----------
VPVUW | TWMHUUTLU
       -RUUWM
        =====
         TLUHU
        -RUUWM
         =====
         VNYUHT
        -VNXQNZ
         ======
           MXVGL
          -MNZJN
           =====
            PJRLU
           -JUXXH
            =====
            ?????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: medium