Q7 quiz 1 question , what will be its answer

Q7. stl lower_bound in set
What will be the output of the following C++ code?

#include
#include
#include
using namespace std;
int main()
{
sets;
s.insert(1);
s.insert(5);
s.insert(7);
s.insert(2);
s.insert(12);
s.insert(10);
auto it = s.lower_bound(15);
cout<< *it <<endl;
return 0;
}

@goyal431 hey, its answer will be 6 ,as 15 is highest and not present in set so it will give last index+1 as answer.