#ifndef NODE
#define NODE
#include<assert.h>
template<class T> class node
{
public:
     node(T value);
     node(T value,node<T>* left,node<T>*right);
     T value;
     node<T>* copy()const;
     void release();
     node<T>*left()const;
     void left(node<T>*l);
     node<T>*right()const;
     void right(node<T>*r);
protected:
     node<T>* leftptr;
     node<T>* rightptr;
};
template<class T>node<T>::node(T value)
                         :value(value),leftptr(0),rightptr(0)
                         {}
template<class T>node<T>::node(T value,node<T>*left,node<T>*right)
                         :value(value),leftptr(left),rightptr(right)
                         {}
template<class T>node<T>* node<T>::copy()const
{
   node<T>*nl,*nr;
   nl=(leftptr==0?0:leftptr->copy());
   nr=(rightptr==0?0:rightptr->copy());
   node<T>*n=new node<T>(value,nl,nr);
   assert(n!=0);
   return n;
}
template<class T>void node<T>::release()
{
   if(leftptr)
   {
      leftptr->release();
      delete leftptr;
      leftptr=0;
   }
   if(rightptr)
   {
      rightptr->release();
      delete rightptr;
      rightptr=0;
   }
}
template<class T> node<T>* node<T>::left()const{
    return leftptr;
}
template<class T> void node<T>::left(node<T>*l){
    leftptr=l;
}
template<class T> node<T>* node<T>::right()const{
    return rightptr;
}
template<class T> void node<T>::right(node<T>*r){
    rightptr=r;
}
#endif