# Write Python code that assigns to the 
# variable url a string that is the value 
# of the first URL that appears in a link 
# tag in the string page.
# Your code should print http://udacity.com
# Make sure that if page were changed to

# page = '<a href="http://udacity.com">Hello world</a>'

# that your code still assigns the same value to the variable 'url', 
# and therefore still prints the same thing.

# page = contents of a web page
page =('<div id="top_bin"><div id="top_content" class="width960">'
'<div class="udacity float-left"><a href="http://udacity.com">')
start_link = page.find('<a href=')

length_ahref=len('<a href=')

start_quote=page.find('"',start_link)
end_quote=page.find('"',start_quote+1)

url=page[(start_quote+1):(end_quote)]
print(url)