function changevalplus() {
a = eval(document.mapper.map.value)
b = eval(document.mapper.current.value)

c = eval(a + b)
document.mapper.map.value = eval(c)
//alert(c)
if(c >= 3) {
MM_swapImage('plus','','Images/null.gif',1)
document.mapper.map.value = 3
}
if(c < 5) {
MM_swapImage('minus','','Images/minus.gif',1)
changemap()
}
}

function changevalminus() {
a = eval(document.mapper.map.value)
b = eval(document.mapper.current.value)

c = eval(a - b)
document.mapper.map.value = eval(c)
//alert(c)
if(c < 1) {
MM_swapImage('minus','','Images/null.gif',1)

document.mapper.map.value = 0
}
if(c < 5) {
MM_swapImage('plus','','Images/plus.gif',1)
changemap()
}
}

   var bannerAD=new Array();
   var adNum=0;

 bannerAD[0]="Maps/District.jpg";
 bannerAD[1]="Maps/suburb.jpg";
 bannerAD[2]="Maps/area.jpg";
 bannerAD[3]="Maps/road.jpg";

function changemap() {
m = eval(document.mapper.map.value)
MM_swapImage('main_map','',bannerAD[m],0)
}