command line - How to provide multiple input to ffmpeg?

I'm using ffmpeg to create time-lapses and it's working great. As input I have images named 001.jpg, 002.jpg, etc. and then with the command

ffmpeg -i %3d.jpg -sameq -s 1440x1080 video.mp4

I create the video. But my problem comes when I want to create a video using multiple sets as input. For example, I'm in a dir where I have two folders set1 and set2, each with photos in it in the format explained previously.

I already tried doing

ffmpeg -i ./set1/%3d.jpg -i ./set2/%3d.jpg -sameq -s 1440x1080 video.mp4

but it ends up doing a video using only the first set. Is there an easy way to do this?

Thanks!