Excel and time attendance resolving how many time user was IN and OUT

Hello,
i have been struggling with this issue but cannot resolve it,hope someone could help me with this.

I have access control wich has export to excel .
In this exported table there are some fields like user name , time , IN (user goes in the office) , OUT (user goes out of the office) .
I was trying to calculate time user has spent inside office for specified time range.
Here is attached output from access control.
Swipe Records-2013-08-21_082227_01.xls

thanks

Hi Amy_d2 ,
first of all thank you for helping me with this,appreciate it.

Yes i have seen that user didnt swipe properly.
Here is another export with proper swipe.Swipe Records.xls
Also if user by mistake swipe two times is there a formula to somehow ignore and use one record?
Here is example:

Sale 12:15 in
Sale 12:22 exit
Sale 12:23 exit

Can we calculate last time (12:23 exit ) and ingore 12:22 time?

I have make an error in thread name...i do not need how many time user has ben inside and out....i need time spend in ,( how many time user has been inside office...2hour,4hour..etc..)