Program ACS simulates an airline check-in system.

To use ACS:
Step 1: execute "make" in terminal to compile ACS
Step 2: execute "./ACS <input file>" in terminal to run ACS

To build your own input txt file:
The first line contains the total number of customers that will be simulated.
For every customer:
1.  The first character specifies the unique ID of customers.
2.  A colon immediately follows the unique number of the customer.
3.  Immediately following is an integer that indicates the arrival time of the customer.
4.  A comma immediately follows the previous number.
5.  Immediately following is an integer that indicates the service time of the customer.
6.  A newline ends a line.

A sample input file is included (in.txt).