#include <iostream>
#include <sstream>
using namespace std;

template <int N> struct Array : Array <N - 1>
{
    double x;
    
    template<int M> double& comp() { return Array<M>::x; }
    template<int M> const double& comp() const { return Array<M>::x; }
    
    //Prints vector
    ostream& print(ostream& out) const
    {
        static_cast<const Array<N-1>*>(this)->print(out);
        out << ", " <<x;
        return out;
    }
    
    double& operator[] (size_t i) {
    	if (i == N - 1) {
        	return x;
    	}
    	return Array<N - 1>::operator[](i);
	}

    
    //Vector in place summation, without looping
    Array& operator+=(const Array& v)
    {
        x+=v.x;
        *static_cast<Array<N-1>*>(this) += static_cast<const Array<N-1>&>(v);
        return *this;
    }
};

template <> struct Array<1>
{
    double x;
    
    template<int M> double& comp() { return Array<M>::x; }
    template<int M> const double& comp() const { return Array<M>::x; }
    
    //Prints vector
    ostream& print(ostream& out) const
    {
        out << x;
        return out;
    }
    
    double& operator[](size_t i) {
    	if (i != 0) { // If you don't care about strange behavior, you can remove this.
        	throw std::out_of_range("Oops!");
    	}
    	return x; 
	}
    
    //Vector in place summation, without looping
    Array& operator+=(const Array& v)
    {
        x+=v.x;
        return *this;
    }
};

template<int N>
ostream& operator<<(ostream& out, const Array<N>& v)
{
    out << "("; v.print(out); out << ")";
    return out;
}

int main() {
	Array<3> vec;
	
	vec[0] = 1; vec[1] = 2; vec[2] = 3;
	
	cout << vec << endl;
	
	cout << (vec+=vec) << endl;
	
	return 0;
}