Numerical Methods: Euler to Runge–Kutta · Medium problem

Euler's method with $n$ equal steps on $y' = -y$, $y(0) = 1$, over $[0,1]$ gives the estimate $\left(1 - \dfrac{1}{n}\right)^n$ of $y(1) = e^{-1}$. Checking small values of $n$ directly, what is the smallest $n$ for which this estimate is within $0.05$ of the true value $e^{-1}$?