function limpaCampo(id) {
    document.getElementById(id).value = "";
}

function areaatuacao(id) {
    if (id == null) {
        alert("Sem argumentos")
        return false
    } else {
        for (var i = 0; i < 6; i++) {
            document.getElementById("aa" + i).style.display = "none"
            document.getElementById("bb" + i).style.color = "#999"
        }

        document.getElementById("aa" + id).style.display = "block"
        document.getElementById("bb" + id).style.color = "#000"
        return true;
    }
}

function areaatuacaoauto() {
    var num = Math.floor(Math.random() * 5);

    for (var i = 0; i < 6; i++) {
        document.getElementById("aa" + i).style.display = "none"
        document.getElementById("bb" + i).style.color = "#999"
    }

    document.getElementById("aa" + num).style.display = "block"
    document.getElementById("bb" + num).style.color = "#000"
}

window.setInterval('areaatuacaoauto()', 5000);