var how_many_ads = 11;
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;

if (ad==1) {
url="c_basico.shtml";
alt="";
banner="ran/v02.gif";
width="138";
height="140";
}

if (ad==2) {
url="c_previsao1.shtml";
alt="";
banner="ran/v06.gif";
width="138";
height="140";
}
if (ad==3) {
url="c_dina_prev.shtml";
alt="";
banner="ran/v10.gif";
width="138";
height="140";
}
if (ad==4) {
url="c_relaciona.shtml";
alt="";
banner="ran/v14.gif";
width="138";
height="140";
}
if (ad==5) {
url="c_mundial.shtml";
alt="";
banner="ran/v18.gif";
width="138";
height="140";
}
if (ad==6) {
url="c_vocacional.shtml";
alt="";
banner="ran/v22.gif";
width="138";
height="140";
}
if (ad==7) {
url="c_horaria.shtml";
alt="";
banner="ran/v26.gif";
width="138";
height="140";
}
if (ad==8) {
url="c_primarias.shtml";
alt="";
banner="ran/v30.gif";
width="138";
height="140";
}

if (ad==9) {
url="c_basico.shtml";
alt="";
banner="ran/v02.gif";
width="138";
height="140";
}

if (ad==10) {
url="c_basico.shtml";
alt="";
banner="ran/v02.gif";
width="138";
height="140";
}

if (ad==11) {
url="oficinas_antropologia.shtml";
alt="";
banner="ran/v42.gif";
width="138";
height="140";
}