var b=0

if((navigator.userAgent.match(/iPhone/i)) || (navigator.userAgent.match(/iPod/i)))
{
b=1;
}
else if((navigator.userAgent.match(/MSIE/i)) || (navigator.userAgent.match(/msie/i)) || (navigator.userAgent.match(/Internet Explorer/i)))
{
b=2;
}
else {
b=3;
}