Calculating Employee Headcount by month.

Hi,

I need calculate monthly total employee headcount for the past few years using employee transaction data. I have 2 columns of start dates (Temp and Full-Time), Status column(Active/Inactive), and Termination Dates. I am finding that there are 2 ways i can approach this problem. The first is to take a running count of employees based solely on their start and end dates. The second is to begin with the current months total number of employees and work my way backwards by adding the terminations for the ith month and subtracting the new hires from the ith month. I am having difficulty translating either approach into an excel formula. I have attached a sample of my employee data.

Thank you in advance.