node, 49 bytes

Result

WA

Code [DL]

g=require('fs');g.readFile(0,(e,l)=>g.write(1,l))

stdin

3864551314346092192653162056127684748892848124422411346752835713660032977721513525170635808591981098

stdout

3864551314346092192653162056127684748892848124422411346752835713660032977721513525170635808591981098

stderr

(node:5) DeprecationWarning: Calling an asynchronous function without callback is deprecated.

strace