????????
      +---------
EEPHG | CUMMPEHH
       -EEPHG
        =====
         MENHE
        -EEPHG
         =====
         UTMTGH
        -PCEREN
         ======
          RPENPH
         -QHCQMG
          ======
          ??????

base: 12
letters: CEGHMNPQRTUX
difficulty: medium
missing: X