Your kneecap (patella) sits over the front of your knee joint. As you bend or straighten your knee, the underside of the patella glides over the bones that make up the knee. Strong tendons help attach the kneecap to the bones and muscles that surround the knee.
NETWORKDAYS.INTL(D3,E3,0000000) calculates whole days between the two dates (no weekends, no holidays). NETWORKDAYS(D3,E3,0000000,$A$16:$A$24) calculates whole working days days between the two dates (Sat/Sun weekends, holidays as per your list in $A$16:$A$24). Difference in non-working days between the two dates.
Supposing today is 2/15/2014, your vacation starts on 12/25/2013 as following screenshot shown, and you want to count how many days there are between these two dates. In a blank cell, please enter this formula =B2-B1, then press Enter key, and you will get the number of days between the two dates. See screenshots: