function switchTo(id) {
    document.getElementById('slide1').style.display=(id==1)?'block':'none';
    document.getElementById('slide2').style.display=(id==2)?'block':'none';
    document.getElementById('slide3').style.display=(id==3)?'block':'none';
    document.getElementById('slide4').style.display=(id==4)?'block':'none';
    document.getElementById('switch1').style.fontWeight=(id==1)?'bold':'normal';
    document.getElementById('switch2').style.fontWeight=(id==2)?'bold':'normal';
    document.getElementById('switch3').style.fontWeight=(id==3)?'bold':'normal';
    document.getElementById('switch4').style.fontWeight=(id==4)?'bold':'normal';
}