function overlap(ss,dz,hsdate,hedate)
{
durms = dz*86400000;
se = ss + durms;

var dateArray = hsdate.split('/');
hstemp = new Date(dateArray[2],dateArray[1]-1,dateArray[0]);
hs = hstemp.getTime();

var dateArray = hedate.split('/');
hetemp = new Date(dateArray[2],dateArray[1]-1,dateArray[0]);
he = hetemp.getTime();
//holiday end is midnight of last holiday day, i.e. beginning of next day; so, add a day
he = he + 86400000;

holms = 0;
if (ss < hs && se > hs && se < he )
{holms = se - hs ;}
if (ss > hs && se > he && ss < he )
{holms = he - ss ;}
if (ss >= hs && se <= he )
{holms = durms ;}
if (ss <= hs && se >= he )
{holms = he - hs ;}

//hold is holidaydays
hold = 0;
hold = Math.round(holms/86400000);

return hold
}