function go_left()
{
	if(k<n-1){
		pos = document.getElementById("sc_ul"); 
		marl = marl + 148;
		pos.style.marginLeft = -marl + "px";
		k++;
	}
}
function go_right()
{
	if(k>0){
		pos = document.getElementById("sc_ul"); 
		marl = marl - 148;
		pos.style.marginLeft = -marl + "px";
		k--;
	}
}