Numerical Methods: Euler to Runge–Kutta · Hard problem

The midpoint method advances by $y_{n+1} = y_n + h\,f\!\left(t_n + \dfrac{h}{2},\ y_n + \dfrac{h}{2}f(t_n, y_n)\right)$. Apply two steps with $h = \dfrac{1}{2}$ to $y' = -y$, $y(0) = 1$, to estimate $y(1)$. Express your answer as a common fraction.