#include <iostream>

template<class T>
void hello(T val) {
	std::cout << "Hello: " << val << "\n";
}

template<class T>
void bye(T val) {
	std::cout << "Bye: " << val << "\n";
}

template<class T>
struct HelloSayer {
	void operator()(T val) {
		hello(val);
	}
};

template<class T>
struct ByeSayer {
	void operator()(T val) {
		bye(val);
	}
};

template<template<class> class Function>
void sayHelloOrBye(int val) {
	Function<int>()(val);
}

int main() {
	sayHelloOrBye<HelloSayer>(4);
	sayHelloOrBye<ByeSayer>(5);
}