template<class InputIterator1, class InputIterator2>
bool includes(InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2);
template<class InputIterator1, class InputIterator2, class Compare>
bool includes(InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
Compare comp);
Returns: true if [first2,last2) is empty or if every element in the range [first2,last2) is contained in the range [first1,last1). Returns false otherwise.
Complexity: At most 2 * ((last1 - first1) + (last2 - first2)) - 1 comparisons.