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

typedef set<int, less<int>, allocator<int> > Set;

int main () {
    int a[] = {1, 2, 3};
    int b[] = {2, 3, 4};

    Set seta (a, a + sizeof a / sizeof *a);
    Set setb (b, b + sizeof b / sizeof *b);

    Set setc;
    insert_iterator<Set> setc_itr (setc, setc.begin ());
    set_union (seta.begin (), seta.end (),
               setb.begin (), setb.end (), setc_itr);

    copy(setc.begin(), setc.end(),
         ostream_iterator<int>(cout, " ") );
    cout << endl;
    return 0;
}