#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using ll =  long long ;
using P = pair<int,int> ;
const ll INF = 1e14;
const int MOD = 1000000007;

int main(){
    string s;
    cin >> s;
    vector<char> a;
    rep(i,s.size()) a.push_back(s[i]);
    sort(a.begin(),a.end());
    reverse(a.begin(),a.end());
    rep(i,a.size()) cout << a[i] ;
    cout << endl;
    return 0;
}