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 class SimplyLinkedList<A> {
  A head;
  SimplyLinkedList<A> tail;
  
  static <B> SimplyLinkedList<B> cons(B head, SimplyLinkedList tail) {
    SimplyLinkedList<B> l = new SimplyLinkedList();
    l.head = head;
    l.tail = tail;
    return l;
  }
}}