????????
      +---------
HVGWX | NLQYZXGG
       -HVGWX
        =====
        UXHXHX
       -UMTPHR
        ======
         XUTQGG
        -XMHRTU
         ======
          VPXUTG
         -VHLWUY
          ======
          ??????

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