Working Time Formula Excel, Need Help Please

Hello, I am working right now with an Access Point Report. They ask me to take out how many Hours a day a person works having this table: 

 

Day	Time	Access Point	Name
3-Jan-2017	7:21:05	Office	Francisco
3-Jan-2017	7:36:21	Office	Marielos
3-Jan-2017	7:41:28	Office	Flor
3-Jan-2017	13:01:45	Office	Flor
3-Jan-2017	13:02:21	Office	Francisco
3-Jan-2017	14.08.23	Office	Flor
3-Jan-2017	13:08:09	Office	Francisco
3-Jan-2017	13:34:55	Office	Francisco
3-Jan-2017	15:48:05	Office	Francisco
3-Jan-2017	17:46:00	Office	Flor
3-Jan-2017	17:49:55	Office	Francisco
3-Jan-2017	17:51:14	Office	Marielos

 

The problem is that there is only ONE sensor and they have to press it every time they enter or they get out, but there is no way of differentiating what is an ENTER and what is a OUT unless you look at the time adn you analyze that the first hour is entering the office and the second our is when they get out, and so on. 

 

I am trying to find a way to calculate this working time automatically because there are 15 employees and more than 300 days and more to come. I found a way but it is hard to apply as you have to filter day by day. 

 

=IF($D$2="Francisco",IF=D3="Francisco",IF(C4>$B$2,SUM(B3-$B$2),""),""),"")

And the you apply a sum to the Resulting values to calculate the working time... but it is a long process day by day, employee by employee. 

 

Is there another way to do it? Thanks very much!