@Gaurav Parmar
If you are asking about the numbers : 1324256400 (Monday, December 19, 2011 1:00:00 AM) and 1324303200 (GMT: Monday, December 19, 2011 2:00:00 PM), they are the epoch timestamp.
I am not sure about your use case on how/when are you going to supply the timestamp.
But, this is one reference to convert human readable dates and time to timestamps and vice versa.
https://www.epochconverter.com/