????????
      +---------
UFUFX | XTLUJQQG
       -UFUFX
        =====
        FXUJQQ
       -FRWRXJ
        ======
         HWXGFQ
        -HJJJRE
         ======
          JRLUUG
         -JMUMGW
          ======
          ??????

base: 13
letters: EFGHJLMQRTUWX
difficulty: medium