????????
      ----------
YVJVH ) TJUUJLWL
       -QWHWT
        =====
        YRXLRL
       -YUPLQX
        ======
         UQJWYW
        -UVZTZL
         ======
          RUHMVL
         -RGUPGN
          ======
          ??????

base: 16
symbols: GHJLMNPQRTUVWXYZ
difficulty: medium