#include <iostream>
#include <list>
using namespace std;

void printl(const list<int> &l) {
    cout << "list:";
    for (list<int>::const_iterator lit = l.begin();
	 lit != l.end();
	 lit++) {
        cout << ' ' << *lit;
    }
    cout << endl;
}

int main() {
    list<int> l;
    list<int>::iterator lit = l.insert(l.begin(), 5);
    l.push_front(0);
    l.push_front(0);
    l.push_back(9);
    l.push_back(9);
    printl(l);
    l.insert(lit, 4);
    printl(l);
}