Replaced 'at()' method with 'operator[]' to improve performance.
The 'at()' method performs bounds checking, which can introduce overhead. Using 'operator[]' bypasses this check and can improve performance when you are certain that the index is within bounds.
Reported by: PVS-Studio
Signed-off-by: Vyacheslav Ivanov <islavaivanov76@gmail.com>
f3f872c7a3