For Rs.28000/- in NSC invested on Jan,2011 amount of Interest exempted for IT during 2011-12 may be informed

Question

We have invested Rs.28000/- in NSC on Jan,11 and claimed exemption U/S 88 in 2010-11 accounting year. Now we have to claim interest exemption for 2011-12 accounting year. Please inform the amount that i can claim as exemption