????????
      +---------
GEEFH | RERMFGFP
       -EJGLT
        =====
        GEYLPG
       -GYJYJG
        ======
         GYMPJF
        -GYJYJG
         ======
           PNJNP
          -GEEFH
           =====
           ?????

base: 13
letters: EFGHJLMNPQRTY
difficulty: medium
hints: Q << T
missing: Q