function adiciona_tel() {
var c = document.forms[0].telefone.value.length;
if(c == 0){
document.forms[0].telefone.value += "(";
}
if(c == 3){
document.forms[0].telefone.value += ") ";
}
if(c == 9){
document.forms[0].telefone.value += "-";
}
}