????????
      +---------
MNHJT | GNGEMUEW
       -MNHJT
        =====
        FRUJFU
       -FURGNJ
        ======
         TJNURE
        -TUGERQ
         ======
           JTXFW
          -UTXQM
           =====
           ?????

base: 13
letters: EFGHJMNQRTUWX
difficulty: medium