????????
      +---------
ZUQQL | UTUWQTVM
       -QGJJP
        =====
        HPRVZT
       -HHXTZX
        ======
         LVRVYV
        -LWJGNX
         ======
          HYJVTM
         -HUYPHJ
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard