#include <iostream>
#include <list>

std::list<int> myList;

void print()
{
    if (!myList.empty())
    {
	    for (auto data : myList) {
        	std::cout << data << " ";
	    }
    }
    else
    	std::cout << "<empty>";
    std::cout << "\n";
}

int main()
{
    myList.push_front(10);
    myList.push_front(20);
    myList.push_front(30);
    print();

    myList.pop_back();
    myList.push_front(40);
    print();

    myList.clear();
    print();

    return 0;
}