var pos=1;

function weiter() {
  if (thumbs.length>5) {
	  for (i=0;i<thumbs.length;i++) {
	    im=thumbs[i];
	    imid=im.id;
	    imnr=eval(imid.replace("im",""));
	    leftPos=eval(im.style.left.replace("px",""));
		first=1-pos;
		if (first<0) {
		  first+=thumbs.length;
		}
		if (i != first) {	
		  leftPos-=120;
		}
		else {
		  leftPos=50+(thumbs.length-1)*120;
		}
	    im.style.left=leftPos+"px";
	  }
	  if (pos>1) {
	  	pos-=1;
	  }
	  else {
	  	pos=thumbs.length;
	  }
  }
}

function rueck() {
  if (thumbs.length>5) {
	  for (i=0;i<thumbs.length;i++) {
	    im=thumbs[i];
	    imid=im.id;
	    imnr=eval(imid.replace("im",""));
	    leftPos=eval(im.style.left.replace("px",""));
		if (i != thumbs.length-pos) {	
		  leftPos+=120;
		}
		else {
		  leftPos=50;
		}
	    im.style.left=leftPos+"px";
	  }
	  if (pos<thumbs.length) {
	  	pos+=1;
	  }
	  else {
	  	pos=1;
	  }
  }
}