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 {

final static class SimpleStack<A> extends RandomAccessAbstractList<A> {
  ArrayList<A> l = new ArrayList();
  int peak;
  
  public A get(int i) { return l.get(i); }
  public int size() { return l.size(); }

  public A set(int i, A a) { return l.set(i, a); }
  public void add(int i, A a) { l.add(i, a); checkSize(); }
  public A remove(int i) { A a = l.remove(i); checkSize(); return a; }
  
  void checkSize() {
    int n = size();
    if (n > peak) peak = n; // record new peak size (~actual capacity)
    if (n*2 < peak) { // shrink physically when below half of peak
      
      trimToSize(l);
      peak = n;
    }
  }
}
static <A> List<A> trimToSize(List<A> l) {
  synchronized(l) {
    if (l instanceof ArrayList)
      ((ArrayList) l).trimToSize();
    
  }
  return l;
}


abstract static class RandomAccessAbstractList<A> extends AbstractList<A> implements RandomAccess {
}
}