????????
      +---------
UKLNK | KTUYHFFF
       -KRYYH
        =====
         YXNNF
        -UKLNK
         =====
         UYFNUF
        -UUHUHY
         ======
          UYTFRF
         -UUHUHY
          ======
          ??????

base: 10
letters: FHKLNRTUXY
hints: L << F
difficulty: hard