????????
      +---------
WMVNJ | ZYWPGRMN
       -WMVNJ
        =====
        UYYUZR
       -UZPTJU
        ======
         RHYWJM
        -TGQMNX
         ======
          TJWVYN
         -JYNYTN
          ======
          ??????

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