php, 42 bytes

Result

WA

Code [DL]

<?=$a=str_split(readline())?implode($a):0;

stdin

2896629632089988236312520190759177701905592750544971360657827371322767196012582780895364408110550138

stdout

stderr

PHP Notice:  Undefined variable: a in /volume/CODE on line 1
PHP Warning:  implode(): Argument must be an array in /volume/CODE on line 1

strace