Updating a map after every loop iteration in C++ 11

I have a loop, which is calculating the size of second member of the p,

where p is std::pair<const std::string, std::set<std::string>>

for (const auto& p : ref)
    std::cout << p.second.size() << endl;

Now I want to create another map cnt (std::map cnt;), which saves p.first and p.second.size() after every iteration. how can I do that?