How do I obtain the days, hours, min and sec between two date/time stamps represented in an excel spreadsheet?

For example:

I have "4/6/2005 10:00:00 AM" in cell A1 and "4/4/2005 7:00:00 AM" in cell A2. How can I obtain the dd:hh:mm:ss between both date/time stamps in cell A3?

A
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1 4/6/2005 10:00:00 AM
2 4/4/2005 7:00:00 AM
3 ??Days, ??Hrs, ??Min, ??Sec