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 <A, B> void removeAllKeysNotIn(Map<A, B> a, Map<A, ?> b) {
  if (a != null) removeAllBut(a, keys(b));
}
static <A> void removeAllBut(Set<A> a, Collection<A> b) {
  if (a != null) for (Iterator<A> it = a.iterator(); it.hasNext(); )
    if (!contains(b, it.next()))
      it.remove();
}

static <A, B> void removeAllBut(Map<A, B> a, Collection<A> b) {
  if (a != null) removeAllBut(a.keySet(), b);
}
static <A, B> Set<A> keys(Map<A, B> map) {
  return map == null ? new HashSet() : map.keySet();
}

static Set keys(Object map) {
  return keys((Map) map);
}








static boolean contains(Collection c, Object o) {
  return c != null && c.contains(o);
}

static boolean contains(Object[] x, Object o) {
  if (x != null)
    for (Object a : x)
      if (eq(a, o))
        return true;
  return false;
}

static boolean contains(String s, char c) {
  return s != null && s.indexOf(c) >= 0;
}

static boolean contains(String s, String b) {
  return s != null && s.indexOf(b) >= 0;
}

static boolean contains(BitSet bs, int i) {
  return bs != null && bs.get(i);
}


static boolean eq(Object a, Object b) {
  return a == null ? b == null : a == b || b != null && a.equals(b);
}




static String str(Object o) {
  return o == null ? "null" : o.toString();
}

static String str(char[] c) {
  return new String(c);
}

}