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> List<A> withoutNulls(Iterable<A> l) {
  if (l instanceof List)
    if (!containsNulls(((List) l))) return ((List) l);
  List<A> l2 = new ArrayList();
  for (A a : l)
    if (a != null)
      l2.add(a);
  return l2;
}

static <A, B> Map<A, B> withoutNulls(Map<A, B> map) {
  Map<A, B> map2 = similarEmptyMap(map);
  for (A a : keys(map))
    if (a != null) {
      B b = map.get(a);
      if (b != null)
        map2.put(a, b);
    }
  return map2;
}

static <A> List<A> withoutNulls(A[] l) {
  List<A> l2 = new ArrayList();
  if (l != null) for (A a : l)
    if (a != null)
      l2.add(a);
  return l2;
}
static boolean containsNulls(Collection c) {
  return contains(c, null);
}

static Map similarEmptyMap(Map m) {
  if (m instanceof TreeMap) return new TreeMap(((TreeMap) m).comparator());
  if (m instanceof LinkedHashMap) return new LinkedHashMap();
  
  // default to a hash map
  return new HashMap();
}

static Map similarEmptyMap(Iterable m) {
  if (m instanceof TreeSet) return new TreeMap(((TreeSet) m).comparator());
  if (m instanceof LinkedHashSet) return new LinkedHashMap();
  
  return new HashMap();
}

static <A, B> Set<A> keys(Map<A, B> map) {
  return map == null ? new HashSet() : map.keySet();
}

// convenience shortcut for keys_gen
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 == b || a != null && 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);
}


}