#include <iostream>
#include <vector>
#include <cstdlib>
#include <algorithm>
#include <functional>
#include <string>
using namespace std;
int main() {
	vector<int> v;
	long long size;
	string str;
	cin >> str;
	sort(str.begin(), str.end(),greater<int>());
	cout << str << endl;
	return 0;
}