An Internet service provider has three different subscription packages for its customers:
• Package A: For $9.95 per month 10 hours of access are provided. Additional hours are $2.00 per hour.
• Package B: For $14.95 per month 20 hours of access are provided. Additional hours are $1.00 per hour.
• Package C: For $19.95 per month unlimited access is provided.
Write a program that calculates a customer's monthly bill.