function Vector_add(obj)
{
  this.elements[this.elements.length++] = obj;
}
function Vector_firstElement()
{
  if (this.elements.length > 0) return this.elements[0];
  return null;
}
function Vector_lastElement()
{
  if (this.elements.length > 0) return this.elements[this.elements.length - 1];
  return null;
}
function Vector_elementAt(ind)
{
  if (ind < 0) return null;
  if (ind >= this.elements.length) return null;
  return this.elements[ind];
}
function Vector_size()
{
  return this.elements.length;
}
function Vector_indexOf(obj)
{
   for (var i = 0; i < this.elements.length; i++)
   {
     if (this.elements[i] == obj) return i;
   }
   return -1;
}
function Vector_contains(obj)
{
  return (this.indexOf(obj) != -1);
}
function Vector_clear()
{
  this.elements = new Array();
}
function Vector_remove(obj)
{
  var nelements = new Array();
  for (var i = 0; i < this.elements.length; i++)
  {
    if (this.elements[i] != obj) nelements[nelements.length++] = this.elements[i];
  }
  this.elements = nelements;
}
function Vector_removeElementAt(ind)
{
  var nelements = new Array();
  for (var i = 0; i < this.elements.length; i++)
  {
    if (i != ind) nelements[nelements.length++] = this.elements[i];
  }
  this.elements = nelements;
}

function Vector()
{
 this.elements = new Array();
 this.add = Vector_add;
 this.firstElement = Vector_firstElement;
 this.lastElement = Vector_lastElement;
 this.elementAt = Vector_elementAt;
 this.size = Vector_size;
 this.indexOf = Vector_indexOf;
 this.contains = Vector_contains;
 this.clear = Vector_clear;
 this.remove = Vector_remove;
 this.removeElement = Vector_removeElementAt;
 return this;
}