#include <iostream>
#include <algorithm>
//#include <string.h>
using namespace std;

int main(void) {
    string num;
    cin >> num;
//    char* str = (char*)malloc(sizeof(char) * num.length()+1);
//    strcpy(str, num.c_str());
//    sort(&num[0], &num[num.length()], greater<int>());
    sort(num.rbegin(), num.rend());
    cout << num << endl;
    return 0;
}