What is the output of the following code? class a { public: a() { cout < < "dc" < < endl; } a(const a& other) { cout < < "cc" < < endl; } a& operator=(const a& other) { cout < < "ao" < < endl; return *this; } ~a() { cout < < "destructor! " < < endl; } }; int main() { a arr[3]; arr[0] = arr[1]; a x = arr[0]; x = arr[1]; a y(arr[2]); cout < < "done" < < endl; }