What is the output of this program?
#include <iostream.h>
#include <algorithm.h>
#include <vector.h>
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());
cout << int(it - v.begin());
return 0;
}