var cflag = false;

function change(name) {
	var elem = document.getElementById(name);
	if(elem.src.indexOf("_n") > 0) {
		elem.src = elem.src.replace("_n", "_h");
		cflag = true;
	}
}

function rechange(name){
	var elem = document.getElementById(name);
	if(elem.src.indexOf("_h") > 0 && cflag){
		elem.src = elem.src.replace("_h", "_n");
		cflag=false;
	}
}