I am having trouble figuring out how to sum up the # of overlapping days with lots of date ranges.

I am using Excel 2010 and this is some of my data.
1/14/2012 1/14/2012
1/14/2012 1/14/2012
1/15/2012 1/20/2012
1/16/2012 1/20/2012
2/4/2012 2/5/2012
2/4/2012 2/11/2012
2/4/2012 2/12/2012
2/4/2012 2/13/2012
2/4/2012 2/16/2012
2/11/2012 2/24/2012
2/11/2012 2/24/2012
3/16/2012 3/17/2012
3/24/2012 4/1/2012
3/25/2012 4/1/2012
3/26/2012 3/27/2012
4/21/2012 4/30/2012
4/21/2012 5/5/2012
4/21/2012 5/5/2012
4/22/2012 5/8/2012

I need to add up all the networking days and exclude holiday. Was wondering if there is an easy way to calculate this.

Thanks,

Tuan