#include <iostream>
#include <algorithm>
#include <math.h>
using namespace std;

int main(){
    int b, a[10];
    for ( int i = 0; i < 10; i++ ){
        a[i] = 0;
    }
    string s;
    cin >> s;
    int len = s.size();
    for ( int i = 0; i < len; i++ ){
        b = s[i] - '0';
        a[b] += 1;
    }
    for ( int i = 9; i >= 0; i-- ){
        for ( int j = 0; j < a[i]; j++ ){
        cout << i;
        }
    
    }
    cout << endl;
    return 0;
}