function a(i){
		selecta(i);
	}
	function selecta(i){
		switch(i){
			case 1:
			document.getElementById("a1").style.display="block";
			document.getElementById("a2").style.display="none";
			document.getElementById("a3").style.display="none";
			document.getElementById("a4").style.display="none";
			break;
			case 2:
			document.getElementById("a1").style.display="none";
			document.getElementById("a2").style.display="block";
			document.getElementById("a3").style.display="none";
			document.getElementById("a4").style.display="none";
			break;
			case 3:
			document.getElementById("a1").style.display="none";
			document.getElementById("a2").style.display="none";
			document.getElementById("a3").style.display="block";
			document.getElementById("a4").style.display="none";
			break;
			case 4:
			document.getElementById("a1").style.display="none";
			document.getElementById("a2").style.display="none";
			document.getElementById("a3").style.display="none";
			document.getElementById("a4").style.display="block";
			break;
		}
	}