Small Roth IRA question

[SaltBoy]

Suppose, for example:

1. I contribute $4000 into my Roth IRA on one day.
2. The next day, I decide to withdraw $2000 from my Roth IRA - no penalties, of course, since I'm only withdrawing what I've already contributed.
3. On day three, can I contribute the $2000 back into my Roth IRA without any penalties?

 

[FoBoT]

http://www.irs.gov/pub/irs-pdf/p590.pdf
it says you can do that before the the due date of your return for the year of the contributions

basically you can do that you are suggesting before april 15 each year, but after that you have to meet the distribution rules, age, disability, first home, etc