function cleanup() {
    document.getElementById("a1").className = "";
    document.getElementById("a2").className = "";
    document.getElementById("a3").className = "";
    document.getElementById("a4").className = "";
    document.getElementById("a5").className = "";
    document.getElementById("a6").className = "";
        
    document.getElementById("i1").style.visibility = "hidden";
    document.getElementById("i2").style.visibility = "hidden";
    document.getElementById("i3").style.visibility = "hidden";
    document.getElementById("i4").style.visibility = "hidden";
    document.getElementById("i5").style.visibility = "hidden";
    document.getElementById("i6").style.visibility = "hidden";    
}

function on(o) {
    document.getElementById("i"+o).style.visibility = "visible";
    document.getElementById("a"+o).className = "act";
}