import java.util.*;
import java.util.zip.*;
import java.util.List;
import java.util.regex.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.*;
import java.util.concurrent.locks.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
import javax.swing.table.*;
import java.io.*;
import java.net.*;
import java.lang.reflect.*;
import java.lang.ref.*;
import java.lang.management.*;
import java.security.*;
import java.security.spec.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.imageio.*;
import java.math.*;
class main {

static String getAndClearStringBuffer(StringBuffer buf) {
  if (buf == null) return null;
  synchronized(buf) {
    String s = buf.toString();
    clearStringBuffer(buf);
    return s;
  }
}
static void clearStringBuffer(StringBuffer buf) {
  if (buf != null) {
    buf.setLength(0);
    buf.trimToSize();
  }
}

}