php, 55 bytes

Result

WA

Code [DL]

<?$a=str_split(fgets(STDIN));sort($a)?><?=join('',$a)?>

stdin

0643728214507523822035830661450051971841421656036837561336643985612885873653019951327694931735854899

stdout

<?$a=str_split(fgets(STDIN));sort($a)?>

stderr

PHP Notice:  Undefined variable: a in /volume/CODE on line 1
PHP Warning:  join(): Invalid arguments passed in /volume/CODE on line 1

strace