function random_imglink(){
        var ry= 1;
	var pasta="";

   	var rx=Math.floor(Math.random()*3);
	
	if (rx==0)
	{
	   pasta="impa";
	   ry=1 + Math.floor(Math.random()*27);
	//1 28
	}
	else if(rx==1){ 

	   pasta="eventos";
	   ry=29 + Math.floor(Math.random()*29);
	   
	   
	//29 58
	}else{

	  pasta="cartazes";
	  ry=59 + Math.floor(Math.random()*37);
	//62 91
	}	

	if (ry==0)
	{
		ry=1;
	}

	var href="http://www.impa.br/opencms/pt/album.jsp?nomeP=../galerias/" + pasta + "/impa" + ry + "p.jpg&nomeG=../galerias/" + pasta + "/impa" + ry + "g.jpg"
	var src="http://www.impa.br/opencms/galerias/" + pasta + "/impa" + ry + "p.jpg"
				
	document.write('<a href='+href+'><img src='+src+' border=0></a>')
	}