#include <iostream>
#include <iomanip>
#include <string>
#include <algorithm>
#include <cmath>
using namespace std;
int main(void)
{
char numbers[10];
cin >> numbers;
sort(numbers, numbers + 10);
reverse(numbers, numbers + 10);
int i = 0;
while(numbers[i]!='\0')
{
cout << numbers[i] ;
i++;
}
return 0;
}
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