????????
      +---------
JQUPU | RNRPJJQE
       -MPFFR
        =====
        GNPLHJ
       -GLQJFE
        ======
         NUMXEQ
        -NGQGHQ
         ======
          JEHMLE
         -JGPQUM
          ======
          ??????

base: 13
letters: EFGHJLMNPQRUX
difficulty: medium