????????
      +---------
GGLNU | RRNGJYJN
       -GGLNU
        =====
        UPTTUY
       - ETFUJ
        ======
         MPNPNJ
        -JXPNEN
         ======
          URGYLN
         -UMMXLM
          ======
          ??????

base: 13
letters: EFGJLMNPRTUXY
difficulty: medium