#include <iostream>
#include <vector>
#include <algorithm>
#include <math.h>

#define ALL(x) (x).begin(),(x).end()
#define RALL(x) (x).rbegin(),(x).rend()
#define REP(i,a,n) for(int i = (a);i < (n);i++)
#define PI 3.14159265359
#define MOD 1000000007

using namespace std;

int main(){
    string s;
    cin >> s;
    vector<int> num(10);
    REP(i,0,s.length()){
        num[ s[i] - '0' ]++;
    }
    
    for(int i = 9;i >= 0;i--){
        REP(j,0,num[i])cout << i;
    }
    cout << endl;
    return 0;
}