#include <iostream>
#include <sstream>
#include <math.h>
#include <stack>
#include <set>
#include <algorithm>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <cstdio>
#include <vector>
using namespace std;

#define INF (1 << 30)
#define INFLL (1LL << 60)

int main() {
	string str;
	cin >> str;
	int a[10] = {};
	for(int i = 0;i < str.size();i++){
		a[str[i]-48]++;
	}
	str = "";
	for(int i = 9;i >= 0;i--){
		for(int j = 0;j < a[i];j++){
			stringstream ss;
			ss << i;
			str += ss.str();
		}
	}
	cout << str << endl;
	return 0;
}