function changeTab(tab){
	if (tab == 1) {
		document.getElementById("tab1").style.display = "block";
		document.getElementById("tab2").style.display = "none";
		document.getElementById("tab3").style.display = "none";
		document.getElementById("tab4").style.display = "none";
	}
	else if (tab == 2) {
		document.getElementById("tab1").style.display = "none";
		document.getElementById("tab2").style.display = "block";
		document.getElementById("tab3").style.display = "none";
		document.getElementById("tab4").style.display = "none";
	}
	else if (tab == 3) {
		document.getElementById("tab1").style.display = "none";
		document.getElementById("tab2").style.display = "none";
		document.getElementById("tab3").style.display = "block";
		document.getElementById("tab4").style.display = "none";
	}
	else if (tab == 4) {
		document.getElementById("tab1").style.display = "none";
		document.getElementById("tab2").style.display = "none";
		document.getElementById("tab3").style.display = "none";
		document.getElementById("tab4").style.display = "block";
	}
}