How to export multiple portions of a scene into separate image sequences

Hi. How can I export two separate image sequences from different portions of the same scene?

For example, let’s say I have a 100 frame animation of a character jumping, with the apex of the jump at frame 51. How can I export an image sequence like this:

Frames 1-50 are exported to Jump001.png, Jump002.png…
Frames 51-100 are exported to Land001.png, Land002.png…

Crucially, none of the Jump frames should export to the Land sequence, and vice versa. And the process needs to happen automatically when I Render Write Nodes - I don’t want to have to manually adjust things each time (eg. entering different start and end frames into the Render Write Nodes dialog) because I export image sequences dozens of times a day, to test them in-game.

There must be a way to do this with Retime nodes or something, but I can’t seem to figure it out.