????????
      +---------
NFJLG | WJGTUTTL
       -NFJLG
        =====
        UMPTGT
       - JNXLU
        ======
         NXNFPT
        -NNURGX
         ======
          RQXQWL
         -RRMGPQ
          ======
          ??????

base: 13
letters: FGJLMNPQRTUWX
difficulty: medium