#include <iostream>
using namespace std;
int main()
{
string s;
cin >> s;
for (int i = 0; i < s.length() - 1; i++)
{
for (int j = i + 1; j < s.length(); j++)
{
if (int(s[i]) > int(s[j]))
{
char t = s[i];
s[i] = s[j];
s[j] = t;
}
}
}
cout << s;
}
I2luY2x1ZGUgPGlvc3RyZWFtPgp1c2luZyBuYW1lc3BhY2Ugc3RkOwoKaW50IG1haW4oKQp7CglzdHJpbmcgczsKCWNpbiA+PiBzOwoKCWZvciAoaW50IGkgPSAwOyBpIDwgcy5sZW5ndGgoKSAtIDE7IGkrKykKCXsKCQlmb3IgKGludCBqID0gaSArIDE7IGogPCBzLmxlbmd0aCgpOyBqKyspCgkJewoJCQlpZiAoaW50KHNbaV0pID4gaW50KHNbal0pKQoJCQl7CgkJCQljaGFyIHQgPSBzW2ldOwoJCQkJc1tpXSA9IHNbal07CgkJCQlzW2pdID0gdDsKCQkJfQoJCX0KCX0KCWNvdXQgPDwgczsKfQo=