var	current_img = 0;
var thumbnail_start = -1;
var	thumbnail_end = -1;
var lg_photo;
	
	function goto_photo (pid) {
		if (pid <= 1 && pid >= -1) {
			if (current_img == 0) current_img = thumbnail_start;
			current_img += pid;
			if (current_img < thumbnail_start) 
				current_img = thumbnail_end - 1;
			else if (current_img > thumbnail_end - 1) 
				current_img = thumbnail_start;				
		} else {
			for (i = thumbnail_start; i < thumbnail_end; i++) {
				if (pid == allIMG[i].src) break;
			}
			current_img = i;		
		}
		
		lg_photob = document.getElementById('lg_photo');
//		lg_photo.alt = allIMG[current_img].alt;
		img_src = allIMG[current_img].src;
		img_src = img_src.replace('sm-im', 'lg-im');
		lg_photob.style.backgroundImage = "url(" + img_src + ")";
	}