#include <iostream>
#include <list>
#include <algorithm>
#include <iterator>
 
void printLinkedList(const std::list<int> &l) {
	for(int x : l) {
		std::cout << x << " ";
	}
    std::cout << std::endl;
}
 
int main() {
    std::list<int> l;
    l.push_back(10);
    l.push_back(20);
    l.push_back(30);
 
    std::cout << "Before copy: ";
    printLinkedList(l);
 
    std:copy_n(l.begin(), l.size(), std::back_inserter(l));
 
    std::cout << "After copy: ";
    printLinkedList(l);
 
    return 0;
}

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