var isNav = (navigator.appName == "Netscape") ? true : false
var isMac = (navigator.appVersion.indexOf("Mac") != -1) ? true : false
var nd=navigator.userAgent.indexOf("Netscape/")
var isNs6=(navigator.userAgent.indexOf("Netscape6/")) ? true : false
var isNs7p = ((nd != -1) && !isMac) ? true : false
var isMoz=(!isMac && (navigator.userAgent.indexOf("Mozilla/5") != -1) && !isNs7p && !isNs6) ? true : false
var isMacIE = ((navigator.appVersion.indexOf("Mac") != -1)&&(navigator.appVersion.indexOf("MSIE") != -1)) ? true : false
var isCa = (navigator.userAgent.indexOf("Camino") != -1) ? true : false
var isSa = (navigator.userAgent.indexOf("Safari") != -1) ? true : false
var isAOL =((navigator.userAgent.indexOf("AOL") != -1) && isMac) ? true : false
if(isNs7p) {
var a1=navigator.userAgent.indexOf(" ",nd)
var aa=parseFloat(navigator.userAgent.substring(nd+9,a1))
if(aa >=7.1)isNs7p=true
else isNs7p=false
} 
var noprev=true
var str=unescape(window.location.href)
//alert(str)
if(str.indexOf("index.html") != -1)noprev=true
else if(str.indexOf(".html") != -1)noprev=false
else noprev=true
//noprev=false

function GetPrev() {
var str
var newstr=""
str=unescape(window.location.href)


   for (var i = 0; i < str.length; i++) {
      var oneChar=str.charAt(i)
      if(oneChar >= "0" && oneChar <= "9") {
         newstr += oneChar       
      }
   }
    pginst=eval(newstr-1)
if(pginst == "0") {
   window.location.href="index.html"
}else {
  window.location.href="busdir"+pginst+".html"
}  
}
  if(!noprev){
document.write('<form><img src="la.gif" onClick="GetPrev()"></form>') 
  }
//    if((isMac||isMoz||isNs7p) && !isMacIE && !isCa  && !isAOL)document.write('<form><input style="font-size:90%" type="button" value=&laquo; onClick="GetPrev()" name="button"></form>');
//    else if (!isNav || isMacIE || isCa||isAOL) document.write('<form><input style="font-size: 90%t" type="button" value=&nbsp;&laquo;&nbsp; onClick="GetPrev()" name="button"></form>');
//    else document.write('<form><input style="font-size:90%" type="button" value=&nbsp;&laquo;&nbsp; onClick="GetPrev()" name="button"></form>');
//  } else document.write('&nbsp;&nbsp;&nbsp;')