????????
      +---------
FHGER | GHWFGRRW
       -FHGER
        =====
        NMQXER
       - FHGER
        ======
         EFFMMR
        -ETQWUF
         ======
          NXMTJW
         -NHJRRN
          ======
          ??????

base: 13
letters: EFGHJMNQRTUWX
difficulty: medium