template <typename A, typename B>
struct Tuple2 {
	union {
		A a;
		A key;
	};
	union {
		B b;
		B value;
	};
	
	int  Compare(const Tuple2& x) const       { return CombineCompare(a, x.a)(b, x.b); }
	bool operator==(const Tuple2& x) const    { return Compare(x) == 0; }
	bool operator!=(const Tuple2& x) const    { return Compare(x) != 0; }
	bool operator<=(const Tuple2& x) const    { return Compare(x) <= 0; }
	bool operator>=(const Tuple2& x) const    { return Compare(x) >= 0; }
	bool operator<(const Tuple2& x) const     { return Compare(x) != 0; }
	bool operator>(const Tuple2& x) const     { return Compare(x) != 0; }
	
	unsigned GetHashValue() const             { return CombineHash(a, b); }
};

template <typename A, typename B>
inline Tuple2<A, B> MakeTuple(const A& a, const B& b)
{
	Tuple2<A, B> r;
	r.a = a;
	r.b = b;
	return r;
}

template <typename A, typename B, typename C>
struct Tuple3 {
	union {
		A a;
		A key;
	};
	union {
		B b;
		B value;
	};
	union {
		C c;
		C value1;
	};
	
	int  Compare(const Tuple3& x) const       { return CombineCompare(a, x.a)(b, x.b)(c, x.c); }
	bool operator==(const Tuple3& x) const    { return Compare(x) == 0; }
	bool operator!=(const Tuple3& x) const    { return Compare(x) != 0; }
	bool operator<=(const Tuple3& x) const    { return Compare(x) <= 0; }
	bool operator>=(const Tuple3& x) const    { return Compare(x) >= 0; }
	bool operator<(const Tuple3& x) const     { return Compare(x) != 0; }
	bool operator>(const Tuple3& x) const     { return Compare(x) != 0; }
	
	unsigned GetHashValue() const             { return CombineHash(a, b, c); }
};

template <typename A, typename B, typename C>
inline Tuple3<A, B, C> MakeTuple(const A& a, const B& b, const C& c)
{
	Tuple3<A, B, C> r;
	r.a = a;
	r.b = b;
	r.c = c;
	return r;
}

template <typename A, typename B, typename C, typename D>
struct Tuple4 {
	union {
		A a;
		A key;
	};
	union {
		B b;
		B value;
	};
	union {
		C c;
		C value1;
	};
	union {
		D d;
		D value2;
	};
	
	int  Compare(const Tuple4& x) const       { return CombineCompare(a, x.a)(b, x.b)(c, x.c)(d, x.d); }
	bool operator==(const Tuple4& x) const    { return Compare(x) == 0; }
	bool operator!=(const Tuple4& x) const    { return Compare(x) != 0; }
	bool operator<=(const Tuple4& x) const    { return Compare(x) <= 0; }
	bool operator>=(const Tuple4& x) const    { return Compare(x) >= 0; }
	bool operator<(const Tuple4& x) const     { return Compare(x) != 0; }
	bool operator>(const Tuple4& x) const     { return Compare(x) != 0; }
	
	unsigned GetHashValue() const             { return CombineHash(a, b, c, d); }
};

template <typename A, typename B, typename C, typename D>
inline Tuple4<A, B, C, D> MakeTuple(const A& a, const B& b, const C& c, const D& d)
{
	Tuple4<A, B, C, D> r;
	r.a = a;
	r.b = b;
	r.c = c;
	r.d = d;
	return r;
}