#include <iostream>
#include <string>
#include <set>
 
int main() {
    std::string line;
    std::getline(std::cin,line);
    
    std::set<char> dict(line.begin(),line.end());
    dict.erase(' ');
    for( const auto &el :dict)
        std::cout<<el;
    std::cout<<std::endl;
    return 0;
}