function trim(cadena){
	
			while (cadena.substr(0,1)==" ")
				cadena=cadena.substr(1);
			while (cadena.substr(cadena.length-1,1)==" ")
				cadena=cadena.substr(0,cadena.length-1);
			while (cadena.search(/  /)!=-1)
				cadena=cadena.replace("  "," "); 
			return(cadena); 
}