????????
      +---------
YMULP | MYLLTYRX
       -YMULP
        =====
        XZPWNY
       -XPNYZG
        ======
         JUUXYR
        -JRRJYJ
         ======
          XGWGQX
         -XGUNHJ
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard
missing: V