Let \([t]\) represent the greatest integer not exceeding \( t \) and \( C = 1 - 2e^2 \).
If the function
\[
f(x) = \begin{cases}
[e^x], & x < 0 \\
ae^x + [x - 2], & 0 \leq x < 2 \\
[e^x] - C, & x \geq 2
\end{cases}
\]
is continuous at \(x = 2\), then \(f(x)\) is discontinuous at: