#include <iostream>
using namespace std;
 
class A {
	int* a;
 
	public:
		A(int* a) {
			this->a = a;
		}
 
		int& operator[](int i) {
			cout << "non-const" << endl;
			return a[i];
		}
 
		const int& operator[](int i) const {
			cout << "const" << endl;
			return a[i];
		}
};
 
void test(const A& a) {
	cout << a[0] << endl;
}
 
int main() {
	int a1[] = {1, 2, 3};
	int a2[] = {4, 5, 6};
	A a(a1);
	const A b(a2);
	cout << a[0] << endl;
	cout << b[0] << endl;
	a[0] = 5;
	test(a);
	return 0;
}

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