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 java.util.function.*;
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 java.awt.geom.*;
import javax.imageio.*;
import java.math.*;
class main {
static List nullPlus(Collection l) {
return itemPlusList(null, l);
}
static List itemPlusList(A a, Collection l) {
return concatLists(ll(a), l);
}
static List concatLists(Iterable... lists) {
List l = new ArrayList();
if (lists != null) for (Iterable list : lists)
addAll(l, list);
return l;
}
static List concatLists(Collection extends Iterable> lists) {
List l = new ArrayList();
if (lists != null) for (Iterable list : lists)
addAll(l, list);
return l;
}
static List ll(A... a) {
ArrayList l = new ArrayList(a.length);
if (a != null) for (A x : a) l.add(x);
return l;
}
static void addAll(Collection c, Iterable b) {
if (c != null && b != null) for (A a : b) c.add(a);
}
static boolean addAll(Collection c, Collection b) {
return c != null && b != null && c.addAll(b);
}
static boolean addAll(Collection c, B... b) {
return c != null && b != null && c.addAll(Arrays.asList(b));
}
static Map addAll(Map a, Map extends A,? extends B> b) {
if (a != null && b != null) a.putAll(b);
return a;
}
}