#include <iostream>
#include <cstring>

using namespace std;

int main()
{
    string n;
    cin>>n;
    int occ[10];
    memset(occ,0,sizeof(occ));
    for(int ctr1=0;ctr1<n.length();ctr1++){
        occ[n[ctr1]-'0']++;
    }
    for(int ctr1=9;ctr1>=0;ctr1--)
        for(int ctr2=0;ctr2<occ[ctr1];ctr2++)
            cout<<ctr1;

    cout<<endl;
    return 0;
}