intersect_stl

#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>
using namespace std;
 long a[1000004],b[1000004],i;

int main()
{

  long n,m;
  cout<<"n=";cin>>n;
  for (i=1;i<=n;i++)
  cin>>a[i];
  cout<<"m=";cin>>m;
  for (i=1;i<=m;i++)
    cin>>b[i];
    sort(a+1, a+n+1);
    sort(b+1, b+m+1);

    vector<int> v_intersection;

    set_intersection(a+1, a+n+1,b+1, b+m+1,back_inserter(v_intersection));
    for(int x : v_intersection)
        cout << x << ' ';
}
//*/