int main(int argc, char **argv) {
	cout << "Hello world";

	SharedPtr<Expression> p1;
    {
        SharedPtr<Expression> p2(new Expression("expr1"));
        SharedPtr<Expression> p3(new Expression("expr2"));
        SharedPtr<Expression> p4(p2);
        SharedPtr<Expression> p5;
        p5 = p2;
        p5 = p4;
        p1 = p5;
        p3.reset();
        p3 = p5;
        p5.reset();
        SharedPtr<Expression> p6;
        SharedPtr<Expression> p7;
        p7 = p7;
        p7.reset();
        p7.reset(new Expression("expr3"));
        SharedPtr<Expression> p8(new Expression("expr4"));
        p8.reset();
    }
    p1 = p1;

	return 0;
}