Problem
Develop a sales-tracking program that enables a company to keep track of its sales force's performance by quarter. The program should read in each person's name and the past performance of that salesperson for the last n quarters, where n is a data item. The operator should be able to enter the results for each person for the current quarter interactively. The operator should be able to add a new salesperson to the system (past performances set to 0) and edit the information stored for a salesperson. The operator should be able to request any of the following tables:
• Total sales by quarter (for all quarters or for a specified quarter)
• Sales for each person by quarter (for all quarters or for a specified quarter)
• Rank of each person by quarter (for all quarters or for a specified quarter)
• A list of salespeople and amounts in decreasing order by quarter (for all quarters or for a specified quarter).