????????
      +---------
JQUYJ | URTZNWUU
       -WWVUN
        =====
         PUTVW
        -QHUGT
         =====
         JNVJPU
        -JYZJLL
         ======
          ZMVJPU
         -ZXGHZU
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: intermediate