function Layer()
{              
    document.getElementById("menudois").style.visibility = 'hidden';
    document.getElementById("menuum").style.visibility = 'hidden';
    document.getElementById("menutres").style.visibility = 'hidden';
    document.getElementById("menuquatro").style.visibility = 'hidden';
}

function Layer1()
{              
    document.getElementById("menuum").style.visibility = 'visible';
    document.getElementById("menudois").style.visibility = 'hidden';
    document.getElementById("menutres").style.visibility = 'hidden';
    document.getElementById("menuquatro").style.visibility = 'hidden';
}

function Layer2()
{              
    document.getElementById("menudois").style.visibility = 'visible';
    document.getElementById("menuum").style.visibility = 'visible';
    document.getElementById("menutres").style.visibility = 'hidden';
    document.getElementById("menuquatro").style.visibility = 'hidden';
}

function Layer3()
{                           
    document.getElementById("menutres").style.visibility = 'visible';
    document.getElementById("menudois").style.visibility = 'hidden';
    document.getElementById("menuum").style.visibility = 'visible';
    document.getElementById("menuquatro").style.visibility = 'hidden';
}

function Layer4()
{              
    document.getElementById("menuquatro").style.visibility = 'visible';
    document.getElementById("menudois").style.visibility = 'hidden';
    document.getElementById("menutres").style.visibility = 'hidden';
    document.getElementById("menuum").style.visibility = 'visible';
}