Example of 'Set' and operations

#include<iostream>
#include <set>
using namespace std;
 
int main()
{
  int someInts[] = {3, 6, 9, 12, 15, 18};
  int someIntsSize = sizeof(someInts) / sizeof(int);
 
  set<int> someSet (someInts, someInts + someIntsSize);
 
  cout<<"\n1. someSet : ";
  copy(someSet.begin(), someSet.end(), ostream_iterator<int>(cout, " "));
  cout<<endl;
 
  //Insert some more elements  someSet.insert(0);
  someSet.insert(10);
  someSet.insert(20);
 
  cout<<"\n2. someSet : ";
  copy(someSet.begin(), someSet.end(), ostream_iterator<int>(cout, " "));
  cout<<endl;
 
  //Upper Bound means the next greater number   set<int>::iterator it = someSet.upper_bound(5);
  cout << "\nupper_bound(5) = " << *it << endl;
 
  it = someSet.upper_bound(10);
  cout << "\nupper_bound(10) = " << *it << endl;
 
  //Lower bound means either equal or greater number  it = someSet.lower_bound(5);
  cout << "\nlower_bound(5) = " << *it << endl;
 
  it = someSet.lower_bound(10);
  cout << "\nlower_bound(10) = " << *it << endl;
 
  //Equal Range returns a pair  pair<set<int>::iterator,set<int>::iterator> retIt;
  retIt = someSet.equal_range(5);
  cout<<"\nequal_range(5) - lower bound = " << *retIt.first << 
    " upper bound = " << *retIt.second << endl;
 
  retIt = someSet.equal_range(10);
  cout<<"\nequal_range(10) - lower bound = " << *retIt.first << 
    " upper bound = " << *retIt.second << endl;
 
  cout<<endl;
  return 0;
}