php, 52 bytes

Result

WA

Code [DL]

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

stdin

1000642247685159799060358008760916245475792939191842148284763532534004859635080372078589674598382513

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