advance http://www.cplusplus.com/reference/std/iterator/advance/

 advance example
#include <iostream>
#include <iterator>
#include <list>
using namespace std;

int main () {
  list<int> mylist;
  for (int i=0; i<10; i++) mylist.push_back (i*10);

  list<int>::iterator it = mylist.begin();

  advance (it,5);

  cout << "The sixth element in mylist is: " << *it << endl;

  return 0;
}