????????
      +---------
ATCAC | QXXQFUQY
       -GTJGJ
        =====
        ATAFCU
       -FYAQTG
        ======
         FQAAQQ
        -FYAQTG
         ======
          XQCQAY
         -XJFGTC
          ======
          ??????

base: 10
letters: ACFGJQTUXY
difficulty: intermediate