function getD1() {
    document.getElementById('a2').style.visibility = "hidden";
    document.getElementById('a3').style.visibility = "hidden";
    document.getElementById('a4').style.visibility = "hidden";
    document.getElementById('a5').style.visibility = "hidden";
    document.getElementById('a1').style.visibility = "visible";
}

function getD2() {
    document.getElementById('a2').style.visibility = "visible";
    document.getElementById('a3').style.visibility = "hidden";
    document.getElementById('a4').style.visibility = "hidden";
    document.getElementById('a5').style.visibility = "hidden";
    document.getElementById('a1').style.visibility = "hidden";
}

function getD3() {
    document.getElementById('a2').style.visibility = "hidden";
    document.getElementById('a3').style.visibility = "visible";
    document.getElementById('a4').style.visibility = "hidden";
    document.getElementById('a5').style.visibility = "hidden";
    document.getElementById('a1').style.visibility = "hidden";
}

function getD4() {
    document.getElementById('a2').style.visibility = "hidden";
    document.getElementById('a3').style.visibility = "hidden";
    document.getElementById('a4').style.visibility = "visible";
    document.getElementById('a5').style.visibility = "hidden";
    document.getElementById('a1').style.visibility = "hidden";
}
function getD5() {
    document.getElementById('a2').style.visibility = "hidden";
    document.getElementById('a3').style.visibility = "hidden";
    document.getElementById('a4').style.visibility = "hidden";
    document.getElementById('a5').style.visibility = "visible";
    document.getElementById('a1').style.visibility = "hidden";
}