c-gcc, 28 bytes

Result

WA

Code [DL]

i;main(){gets(&i);puts(&i);}

stdin

1806780180892356932216362388490550672700681828142784609655402607504035495420553620384830829936197720

stdout

1806780180892356932216362388490550672700681828142784609655402607504035495420553620384830829936197720

stderr

/tmp/code.c:1:1: warning: data definition has no type or storage class
 i;main(){gets(&i);puts(&i);}
 ^
/tmp/code.c:1:1: warning: type defaults to ‘int’ in declaration of ‘i’ [-Wimplicit-int]
/tmp/code.c:1:3: warning: return type defaults to ‘int’ [-Wimplicit-int]
 i;main(){gets(&i);puts(&i);}
   ^
/tmp/code.c: In function ‘main’:
/tmp/code.c:1:10: warning: implicit declaration of function ‘gets’ [-Wimplicit-function-declaration]
 i;main(){gets(&i);puts(&i);}
          ^
/tmp/code.c:1:19: warning: implicit declaration of function ‘puts’ [-Wimplicit-function-declaration]
 i;main(){gets(&i);puts(&i);}
                   ^
/tmp/ccixp7UG.o: In function `main':
code.c:(.text.startup+0xc): warning: the `gets' function is dangerous and should not be used.

strace