rail, 56 bytes

Result

WA

Code [DL]

$ 'dup'
 \
  \-(!a!)(a)(a)#

$ 'main'
 \
  \-[x]{dup}oo#

stdin

4476000752472849370686160371167321186801219225475346115871245773349924653400486015594344928318916903

stdout

xx

stderr

strace