How to turn-off Anti-aliasing when convert video into gif file with ffmpeg

Question

I want to know how can i turn off Anti-aliasing when i convert video into gif file with ffmpeg, Actually i want ouput in 100% pure aliased gif animation. like this sample image

Here i try this but i did not get the results as i expected.

ffmpeg -i video.mp4 -t 5 out.gif

Any help will be appreciated.