using namespace std;

class Base {

public:

    virtual const char* name() { return "Base"; }

    virtual ~Base() {}

};

template <class A1>

class A : public Base {

public:

    virtual const char* name() { return "A"; }

    A1 funcA(A1 x) { return x; }

};

template <class B1, class B2>

class B : public A<B2> {

public:

    virtual const char* name() { return "B"; }

    pair<B1, B2> funcB(B1 x, B2 y) { return pair<B1, B2>(x, y); }

};

template <class C1>

class C : public B<long, C1> {

public:

    virtual const char* name() { return "C"; }

    C1 funcC(C1 x) { return x; }

};

template <class D1>

class D : public C<pair<D1, D1> > {

    virtual const char* name() { return "D"; }

};

class E : public D<double> {

    virtual const char* name() { return "E"; }

};