formula to calculate the number of people

[Sasikiran]

Dear,

I would require a formula to calculate the number of people available for
the task for each half hour time based on login and logout time.

Col A Col B Col C Col E Col F
Name Logintime Logouttime 7:30 = FORMULA
8:00


Shift for the day starts at 7:30 and there will be people who logged at
23:00 last night till 7:30 until the guys join at 7:30.

There will be guys joining one by one after 7:30.

I would require a formula to know the number of people available for each
half hour slot based on the number of people logged in at that time + number
of people who have logged in before and the current time slot is within their
logout time.

Please help me in getting this.