#include <iostream>
// write your code here......
#include<set>
#include <string>

using namespace std;

int main() {

    char str[100] = { 0 };
    cin.getline(str, sizeof(str));

    // write your code here......
    set<char> s;
    for (int i = 0; str[i]!='\0'; i++) {
        s.insert(str[i]);
    }

    for (set<char>::iterator it = s.begin(); it != s.end(); it++) {
        cout << *it;
    }

    return 0;
}