Excel 2007 : Calculating all lunch breaks in Timesheet

I am including an attachment so you can see what my time sheet looks like.

About the time sheet:
The time sheet includes two programs the employee works in: Program A and Program B.

The employee may sign in and out of each program several times a day. Some days they may just work on Program A and not on Program B and vice versa. Some days they might sign in first into Program A or vice versa.

What the time sheet doesn't include is what time lunch was taken, which is what I need to find out because I need to use that for another program time sheet I'm working on.

I cannot change the format of THIS time sheet because that's the way the state wants it. Otherwise, I would just save myself the trouble and include a slot for the employee to input what time they signed in and out of lunch.

Lucky me, the state created the time sheet in excel, so while I cannot change the format of the time sheet, I can tweak some of the formulas to help us out on other excel programs that we use at the office..

So here is my problem:

Normally the employee doesn't take a break between programs, which makes it easy to spot where they had their "lunch break" because it is usually between 30 minutes to 2 hours between sign out and sign in. My problem is, how do I get excel to recognize that lunch break when the sign in and out can start almost anywhere on the sheet?

Also, it is possible for an employee to take their "lunch break" how they want. So if, for example, they want to take an hour off in the morning and then later in the afternoon another hour, they can do that, so long as it doesn't pass two hours. Here is what I mean:

Employee clocks in to program A at 8am and works until 10am. Then at 10am (without a break) he clocks into program B until 12noon. At 12 noon, he takes an hour lunch break and signs back in to Program B at 1pm. He clocks out at 2pm and takes another a break until 2:30pm. he clocks back in to Program A and works until 5:30pm. He takes another 30 minute break and clocks back into Program B at 6pm.

I hope I didn't make this too confusing. Let me know if you need additional details. Again, what I need is for excel to calculate all the "lunch breaks" in the time sheet.

I'm imagining that I can sort all the "Time In" times from earliest to latest and then do the same for "Time Out", and then subtract them from each other and sum up the results, however, if there is an easier way that won't occupy too much space, it would be greatly appreciated.

Thank you.