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

#define rep(i,n) for(int i=0;i<(n);i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
typedef vector<int>vi;

int main(){
    string s;
    cin>>s;
    sort(all(s));
    reverse(all(s));

    cout<<s<<endl;
    return 0;
}