Inheritance of cominated templated types

I would like to make a class that inherits of a combination of two templated types like this for example:

#include <vector>
#include <set>

template<typename T, typename Base=std::vector<T>>
class A : public Base
{
};

int main()
{
    A<int> a;
    A<int, std::set<int>> b;

    return 0;
}

But now, I would like to be able to write

    A<int, std::set> b;

instead of

    A<int, std::set<int>> b;

How can I do this please? Thanks! :)