function show(elmnt_num){
		var iid = 'pi_'+elmnt_num;
		document.getElementById(iid).className = 'pi_top';
		document.getElementById('bimg').className = 'opacity2bi';
	}
	
function remove(elmnt_num){
		var iid = 'pi_'+elmnt_num;
		document.getElementById(iid).className = '';
		document.getElementById('bimg').className = '';
	}