#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
#include<stdio.h>
#include<cmath>
#include<vector>
#include<utility>
#include<stack>
#include<queue>
#include<list>
#include<bitset>
#include<functional>

#define FOR(i, a, b) for(int i=(a);i<=(b);i++)
#define RFOR(i, a, b) for(int i=(a);i>=(b);i--)
#define MOD 1000000007
#define INF 1000000000

using namespace std;

int main(void) {
	string s;
	int dp[10] = {};

	cin >> s;
	FOR(i, 0, s.size() - 1) {
		FOR(t, 0, 9) {
			if (s[i] == '0' + t) {
				dp[t]++;
			}
		}
	}

	RFOR(i, 9, 0) {
		FOR(t, 1, dp[i]) {
			cout << i;
		}
	}
	cout << endl;

	return 0;
}