Complete using C#.
1. Write a program that allows the user to enter any number of integer values continuously (in any order) until the user enters 999. Display the sum of the values entered, not including 999. Save the file as Sum.cs.
2. Three salespeople work at Sunshine Hot Tubs-Andrea, Brittany, and Eric. Write a program that prompts the user for a salesperson's initial ('A', 'B', or 'E'). While the user does not type 'Z', continue by prompting for the amount of a sale the salesperson 157158made. Calculate the salesperson's commission as 10 percent of the sale amount, and add the commission to a running total for that salesperson. After the user types 'Z' for an initial, display each salesperson's total commission earned. Save the file as TubSales.cs.
3. Write a program containing an array that holds five integers. Assign values to the integers. Display the integers from first to last, and then display them from last to first. Save the program as IntegerList.cs.