import java.io.*; import java.util.*; import org.opj.*;

public class Main {   static { OPRuntime.roots.add(Main.class); }   private static Main self = new Main();

  private static List history = new LinkedList();   private float exchangeRate;

 public static void main(String args[]) {     try {       BufferedReader in = new BufferedReader(new InputStreamReader(System.in));       while (true) {         System.out.print("Input a command: ");         int command = in.read(); String arg = in.readLine();         switch (command) {         case 'x':           history.add(0, new Float(self.exchangeRate));           exchangeRate = Float.parseFloat(arg);           System.out.println("Exchange rate set to " + self.exchangeRate);           break;         case 'c':           {             float amount = Float.parseFloat(arg);             System.out.println("Amount " + amount + " converts to " + amount*self.exchangeRate);           }           break;         case 'h':           {             System.out.print("Exchange rate history: " + self.exchangeRate);             ListIterator iter = history.listIterator();             while (iter.hasNext()) {               System.out.print(" " + ((Float)(iter.next())).floatValue());              }             System.out.println("");           }           break;         case 'q':           System.exit(0);           break;         default:           System.out.println("Unknown command " + command);         }         OPRuntime.checkpoint();       }     } catch (Exception e) {       System.out.println(e);       System.exit(-1);     }  }