what is the output of the program given below?

#include <iostream> 
#include <algorithm>
#include <vector>
using namespace std;
int main ()
{
    int first[] = {5, 10, 15, 20, 25};
    int second[] = {50, 40, 30, 20, 10};
    vector<int> v(10);
    vector<int> :: iterator it;
    sort (first, first + 5);
    sort (second, second + 5);
    it = set_union (first, first + 5, second, second + 5, v.begin());  
    v.resize(it-v.begin());
    for (it = v.begin(); it != v.end(); ++it)
        cout << ' ' << *it;
    cout << '\n';
    return 0;
}