Okay, I haven't been on in a while, let me tell you why no one has replied, you haven't showed ANY effort. Let me see the code you have so far and I'll tell you what you're doing wrong and give you suggestions. This is a simple solution, and you would get the answer in 2 seconds by looking at your text book or anyother reference and apply some logic.
The one without indexes is considered often more 'pythonic', but of course sometimes it more usefull to use indexes. You lost your indention in posting code, put empty line and line with ~~~ before and opposite order after you code, or paint it after pasting and push Tab.