function createCookie(name,value,days) {
    if (days) {
        var date = new Date();
        date.setTime(date.getTime()+(days*24*60*60*1000));
        var expires = "; expires="+date.toGMTString();
    }
    else var expires = "";
    document.cookie = name+"="+value+expires+"; path=/";
}
 
function readCookie(name) {
    var nameEQ = name + "=";
    var ca = document.cookie.split(';');
    for(var i=0;i < ca.length;i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') c = c.substring(1,c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
    }
    return null;
}
 
function eraseCookie(name) {
    createCookie(name,"",-1);
}
 
function popup(url){
    var pos;
    if (window.innerHeight){
        pos = window.pageYOffset
    }else if (document.documentElement && document.documentElement.scrollTop){
        pos = document.documentElement.scrollTop
    }else if (document.body){
        pos = document.body.scrollTop
    }
 
        var x=document.documentElement.clientWidth/2-240;
        var y=pos+100;
       
    document.getElementById('popup').style.top=y+'px';
    document.getElementById('popup').style.left=x+'px';
 
    if(blank=document.getElementById('black_overlay'))blank.style.display='block';
    document.getElementById('popup').style.display='block';
 
}
 
function close_popup(){
    if(blank=document.getElementById('black_overlay'))blank.style.display='none';
    document.getElementById('popup').style.display='none';
}
 
window.onload=function(){
        if(readCookie('oldvisitor')==null){
            createCookie('oldvisitor',1,1);
            popup();
        }
}