01. Computer Store (Stoyan Bakardjiev)

command = input()

price = 0

while not (command == 'special' or command == 'regular'):
    data = float(command)
    if data < 0:
        print('Invalid price!')
    else:
        price += data
    command = input()

taxes = price * 0.20
total_price = price + taxes

if command == 'special':
    total_price *= 0.9

if total_price <= 0:
    print('Invalid order!')
else:
    print('Congratulations you\'ve just bought a new computer!')
    print(f'Price without taxes: {price:.2f}$')
    print(f'Taxes: {taxes:.2f}$')
    print('-----------')
    print(f'Total price: {total_price:.2f}$')