COUNTIF between two times

Hi guys,

Hope you can help with this one.

I have a rota that has a big list of names in the rows and days of the week in the columns.

Each cell then says what shift/hours they worked for that day. So for example 08:30 - 15:30.

What I want to do is track how many staff we had in at half an hour intervals.

SO an example output would look like:
08:00 - 102
08:30 - 122
09:00 - 121
09:30 - 125
etc

Where each time represents how many people were working at that particular time.

So far I have tried splitting each person unto two additional columns using LEFT & RIGHT to get their start and stop time, then using a COUNTIFS and TIME function but I can't seem to get it working.

I have attached a simple example of what the data looks like (1st tab) and what the results should look like (2nd tab).

Is anyone able to help me?