public static void doTowers(PrintWriter out,int topN, char from, char inter, char to) {
 	    if (topN == 1){
 	      out.println("Ring 1 from " + from + " to " + to);
 	    }else {
 	      doTowers(out,topN - 1, from, to, inter);
 	      out.println("Ring " + topN + " from " + from + " to " + to);
 	      doTowers(out,topN - 1, inter, from, to);
 	    }
 	  }