#include "string.h"
#include "iostream.h"
#define NULL 0

struct Node
{
	char course[7];
	Node *left;
	Node *right;
};

class unitTree
{
public:
	void add(char course[7]);
	void display();
	unitTree(){root=NULL;}
	
	~unitTree();
private:
	void show(Node* tmp);
	void destroy(Node *);
	Node *root;
};