##Example 1

print("Please enter the ages of the customers one line at a time. \nEnter -1 when there are no more customers.")

age = int(input("Age: "))

bill = 0

while age != -1:
    if age <= 2 and age > 0:
        bill = bill
        
    elif age <=12 and age>2:
        bill = bill + 4.50

    elif age >=65:
        bill = bill + 7.50

    elif age > 12 and age < 65:
        bill = bill + 9
        
    elif age < -1:
        quit()
    
    age = int(input("Age: "))
              
  
bill = '{:,.2f}'.format(bill)
print("The total bill is $"+str(bill))
quit()
     
#########################


##Example 2

print("Please enter the ages of the customers one line at a time.")
print("Enter -1 when there are no more customers.")

age = int(input("Age: "))

price = 0

while age!=-1:
    if age>=3 and age<=12:
        price = price + 4.50
    elif age>=65:
        price = price + 7.50
    elif age>12 and age<65:
        price = price + 9
    age=int(input("Age: "))
    
price = '{:,.2f}'.format(price)
        
print("The total bill is $",price)


#########################


##Example 3

print("Please enter the ages of the customers one line at a time")
print("Enter -1 when there are no more costomers")

customers = True 
total=0
while customers:
    age=int(input("Age: "))
    if age==-1:
        customers = False
    elif age <=2:
        total=total+0
        #print(total)
    elif age >2 and age <=12:
        total=total+4.5
        #print(total)
    elif age >12 and age <65:
        total=total+9
        #print(total)
    elif age >=65:
        total=total+7.5
        #print(total)
    
    
print("The total bill is $",'{:,.2f}'.format(total))