d-gdc, 114 bytes

Result

ERROR

Code [DL]

import std.stdio;import std.array;import std.algorithm;void main(){write(join(sort!("a<b")(split(readln(),""))));}

stdin

0801201977309426321781216538847013711561330723075955323953148113823793146769390138403058746754614949

stdout

stderr

strace