plan = raw_input('Please input if you have plan a, b, or c: ')
while True:
    try:
        hours = float(raw_input('\nHow many hours have you used on your plan: '))
        break
    except ValueError:
        print '\nError: Please enter a number'


if plan == 'a':
    print '\nYou have plan A'
    if hours < 10:
        print 'You have used ' + str(hours) + ' and will be charged ' + str(9.95 + 2 * (hours - 10))
elif plan == 'b':
    print '\nYou have plan B'
    if hours < 20:
        print 'You have used ' + str(hours) + ' and will be charged ' + str(13.95 + hours - 20)
elif plan == 'c':
    print '\nYou have plan C'
    if hours > 20:
        print 'You have used ' + str(hours) + ' and will be charged 19.95'