cppreference.com > C++ Algorithms > includes includes Syntax:
      #include <algorithm>
      bool includes( iterator start1, iterator end1, iterator start2, iterator end2 );
      bool includes( iterator start1, iterator end1, iterator start2, iterator end2, StrictWeakOrdering cmp );
The includes() algorithm returns true if every element in [start2,end2) is also in [start1,end1). Both of the given ranges must be sorted in ascending order. By default, the < operator is used to compare elements. If the strict weak ordering function object cmp is given, then it is used instead. includes() runs in linear time. Related topics: set_difference set_intersection set_symmetric_difference set_union