// JavaScript Document
function show_intro(pre,pree, n, select_n) {
	for (i = 1; i <= n; i++) {
			var intro = G(pre + i);
			var cha = G(pree + i);
			intro.style.display = "none";
			cha.className="menu_off";
			if (i == select_n) {
			intro.style.display = "block";
			cha.className="menu_on";
		}
	}
}
function G(id){return document.getElementById(id);}