What will be the output of the following C++ code?

#include <iostream>
#include <iterator>
#include <list>
using namespace std;
int main () 
{
    list<int> firstlist, secondlist;
    for (int i = 1; i <= 2; i++)
    {  
        firstlist.push_back(i); 
        secondlist.push_back(i * 10); 
    }
    list<int> :: iterator it;
    it = firstlist.begin(); 
    advance (it, 3);
    copy (secondlist.begin(), secondlist.end(), inserter(firstlist, it));
    for ( it = firstlist.begin(); it != firstlist.end(); ++it )
        cout << *it << " ";
    return 0;
}