#include "iostream"
#include "string"

template <typename T>
T f(T x) {
    return x * x;
}

template <typename X>
void input(std::string message, X &target) {
    std::cout << message;
    std::cin >> target;
}

int main() {
    std::string lang = "C";
    std::string version = "++";
    lang = lang + version;
    std::cout << "Hello World, said by " << lang << "!" << std::endl;
    int x = 0;
    input("x = ", x);
    std::cout << "f(x) = " << f<int>(x) << std::endl;
    return 0;
}