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import java.io.*;
import java.lang.reflect.*;
 
class OpenedFile implements Serializable {
  String filename;
  BufferedReader reader;

  public OpenedFile(String _filename) throws FileNotFoundException {
    filename = _filename;
    init();
  }

  private void init() throws FileNotFoundException {
    reader = new BufferedReader(new FileReader(filename));
  }
     
  private void writeObject(ObjectOutputStream out) throws IOException {
    out.writeUTF(filename);
  }

  private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
    boolean hasWhitelist = false;
    try {
        in.getClass().getDeclaredField("whitelist");
        hasWhitelist = true;
    } catch (ReflectiveOperationException e) {}
    if (!hasWhitelist) {
      throw new SecurityException("Deserialization without a whitelist is disallowed for class " + 
                                  this.getClass().getName() + ".");
    }
    filename = in.readUTF();
    init();
  }
}