#include<bits/stdc++.h>
using namespace std;

int main(){
	string n;
	cin >> n;
	int count[10];
	fill(count, count + 10, 0);
	int num;
	for(int i = 0; i < n.length(); i++){
		num = n[i] - '0';
		count[num]++;
	}
	for(int i = 9; i >= 0; i--){
		if(count[i] == 0) continue;
		else{
			for(int j = 0; j < count[i]; j++){
				printf("%d", i);
			}
		}
	}
	cout << endl;
}