CCommunity
Number of odd days in 2005 = 1
Number of odd days from 2005 till 2006 = 1 + 1 = 2
Number of odd days from 2005 till 2007 = 2 + 1 = 3
Number of odd days from 2005 till 2008 = 3 + 2 = 5
Number of odd days from 2005 till 2009 = 5 + 1 = 6
Number of odd days from 2005 till 2010 = 6 + 1 = 7 = 0 odd day
Hence, the calendar of 2005 is same as that of 2011.