3. Solve the system of equations $\left\{\begin{array}{l}y^{2}=x^{3}-3 x^{2}+2 x, \\ x^{2}=y^{3}-3 y^{2}+2 y .\end{array}\right.$
(Solution: $(x, y)=(0,0),(2+\sqrt{2}, 2-\sqrt{2})$, $(2-\sqrt{2}, 2+\sqrt{2})$.