????????
      +---------
ZNHMZ | LRPTMYJY
       -ZNHMZ
        =====
        XZTYTY
       -XXJLJU
        ======
          JNRPJ
         -RTMJM
          =====
          GGGWXY
         - YUXWQ
          ======
          ??????

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