#include <iostream>

#include <cstddef>

using namespace std;

#define __STL_TEMPLATE_NULL template<>

template<class Key>

class hash {

public:

    void operator()() {

        cout << "Hash<T>" << endl;

    }

};

//explicit specialization

__STL_TEMPLATE_NULL

class hash<char> {//template specifiers not specified in declaration of ‘template<class Key> class hash’

public:

    void operator()() {

        cout << "Hash<char" << endl;

    }

};