?????????
      +----------
EQEJL | JQGJJYTFQ
       -EQEJL
        =====
        HXNYHY
       -HUULPN
        ======
         UTTPTT
        -GEHHQT
         ======
          EQGHYF
         -PUPHNF
          ======
           PNXTYQ
          -PUPHNF
           ======
           ??????

base: 13
letters: EFGHJLNPQTUXY
difficulty: intermediate