var GO = function(elemId) {
	return document.getElementById(elemId);
}

function menu(idx) {
	GO("m_"+idx).className = 'on';
	GO("c_"+idx).style.display = "block";

	for(var i=1;i<9;i++) {
		if(!GO("m_"+i)) continue;
		if(i != idx) {
			GO("m_"+i).className = 'off' ;
			GO("c_"+i).style.display = "none";
		}
	}
}