function ApriMenu(i,j,k,z)
{
    document.getElementById("menu_" + i).style.visibility = "Visible";
    document.getElementById("menu_" + j).style.visibility = "Hidden";
    document.getElementById("menu_" + k).style.visibility = "Hidden";
    document.getElementById("menu_" + z).style.visibility = "Hidden";
}
function ApriSottoMenu(i,j,k,z)
{
    document.getElementById("menu_" + i).style.visibility = "Visible";
    document.getElementById("menu_" + j).style.visibility = "Visible";
    document.getElementById("menu_" + k).style.visibility = "Hidden";
    document.getElementById("menu_" + z).style.visibility = "Hidden";
}
function ChiudiMenu(i,j,k,z)
{
    document.getElementById("menu_" + i).style.visibility = "Hidden";
    document.getElementById("menu_" + j).style.visibility = "Hidden";
    document.getElementById("menu_" + k).style.visibility = "Hidden";
    document.getElementById("menu_" + z).style.visibility = "Hidden";
}