#include<iostream>
#include<string>
#include<algorithm>
#include<functional>
#include<vector>
#include<stack>
#include<queue>
#include<set>
#include<map>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
using namespace std;

char s[100002];

signed main() {
	cin >> s;
	int len = strlen(s);
	sort(s, s + len, greater<char>());
	for (int i = 0; i < len; i++)
		cout << s[i];
	cout << endl;
	return 0;
}