Since you are new, I want to give some advice about the site: **To get the best possible answers, you should explain what your thoughts on the problem are so far**. That way, people won't tell you things you already know, and they can write answers at an appropriate level; also, people are much more willing to help you if you show that you've tried the problem yourself. – 2012-07-08
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Thanks for your recommendation Zev Chonoles – 2012-07-09