Show two videos simultaneously

Hi there!

I need your help:

I'm trying to merge two video sequences into one by alternating each sequence every frame.
I have basically the same sequence twice, one is shot in daylight and the other one by night.
Example:
frame 1- video 1 | frame 2 - video 2 | frame 3 - video 1| frame 4 - video 2 ... and so on.

In my head it looks something like this.

I'm not sure how to achieve this effect. Maybe masking one of the two sequences every other frame? Expressions?

Feedback would be very much appreciated.
Cheers. A

Every second frame will be very fast, 5 frames each alternating would be more like it. Adjustable frame count would be something like this:

freq=5;
currTime = Math.round(time/thisComp.frameDuration);
if (currTime%(2*freq) <freq) {value=0}else{value=100}