#include <iostream>
// write your code here......
#include <set>
using namespace std;

int main() {

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

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

    for (auto iter = uniqueChars.begin(); iter != uniqueChars.end(); ++iter) {
        cout << *iter;
    }
    cout << endl;

    return 0;
}