#include <iostream>
#include <string>
#include <set>
int main() {
std::string str = "C++ is a general-purpose programming language";
std::set<char> unique_chars(str.begin(), str.end());
for (char ch : unique_chars) {
std::cout << ch << " ";
}
}
/*
run:
+ - C a e g i l m n o p r s u
*/