Hire a crowd

Some people hire crowds to make something appear to have more support (or opposition) than it does. Ethical? Maybe not, but it does happen.

Write a program to work out the cost of a crowd. You can download a starting worksheet. It looks like this:

Users enter six values at the top of the worksheet, click the button, and get prices. For example:

If there are input errors, your program should report them. Like this:

The rules are:

• Goats is a number from 8 to 80.
• Megaphones is a number from 0 to 80.
• Energy level is H, M, or L. Case shouldn't matter, nor should extra spaces. So " m " is valid.

Also:

• No prices if there are input errors.
• Erase the output and error messages each time the program runs.
• Show all the error messages that apply at the same time.

Pricing rules:

• High-energy goats cost $180 each.
• Medium-energy goats cost $150 each.
• Low-energy goats cost $120 each.
• Megaphones cost $45 each.

Output warnings when:

• For each group (support and opposed), the number of megaphones is greater than the number of goats.
• The number of opposed goats is greater than the number of supporting goats.

Here are some warnings:

Make sure warnings go in the appropriate cells, as shown.

Upload your solution here, not to Moodle. The usual programming standards apply.