determing how many fit

ok new question I am working on a schedule and I wanna figure out how many people are working during each hour. Here is some data

11 a-7p
11a-5p
3p-9p
5p-10p
How can i figure out the number of people working each hour.
11-12
12-1
1-2
2-3
3-4
4-5
5-6
6-7
7-8
8-9
9-10

Any help would be appreciated

John