#include <iostream>
#include <map>

using namespace std;

int main(int argc, const char* argv[])
{
	string s;
	cin >> s;
	map<char, int> m;
	for (auto&& c : s) m[c]++;
	for (int i = 9; i >= 0; i--) {
		char c = '0' + i;
		for (int j = 0; j < m[c]; j++) cout << c;
	}
	cout << endl;
	return 0;
}