#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <cstring>

typedef long long ll;
using namespace std;

#define mod 1000000009
#define INF 10000000
#define LLINF 2000000000000000000LL

#define SIZE 10001

int main(){
    string S;
    
    cin >> S;
    
    sort(S.begin(),S.end());
    reverse(S.begin(), S.end());
    
    cout << S;
    
    return 0;
}