var isWin = false;
var isMac = false;
var isGecko = false;
var isOldNs = false;
var isNewIe = false;
var isOldIe = false;
var isIe4 = false;
var isAncientNs = false;
var isOpera = false;
var isIe = false;
var isNs = false;

if (navigator.appVersion.indexOf('Win') != -1) {
	isWin = true;
} else if (navigator.appVersion.indexOf('Mac') != -1) {
	isMac = true;
}
if (navigator.appName.indexOf('Netscape') != -1) {
	if (navigator.userAgent.indexOf('Opera') == -1) {
		isNs
	}
	if (navigator.userAgent.indexOf('Gecko') != -1) {
		isGecko = true;
	} else if (navigator.userAgent.indexOf('Mozilla/4.') != -1) {
		isOldNs = true;
	} else {
		isAncientNs = true;
	}
}
if (navigator.appName.indexOf('Microsoft' != -1)) {
	isIe = true;
	str1 = navigator.appVersion.split(';');
	if (parseInt(str1[1].charAt(str1[1].lastIndexOf('.')-1)) == 4) {
		isIe4 = true;
	} else if (parseInt(str1[1].charAt(str1[1].lastIndexOf('.')-1)) < 4) {
		isOldIe = true;
	} else if (parseInt(str1[1].charAt(str1[1].lastIndexOf('.')-1)) > 4) {
		isNewIe = true;
	}
}
if (navigator.userAgent.indexOf('Opera') != -1) {
	isOpera = true;
}
if (!isOpera || !isNs || !isIe) {
	isUnknown = true;
}