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struct StringTree
{ string data;
  StringTree * left, * right;
  StringTree(string s): data(s), left(NULL), right(NULL) { }
  void insert(string s);
  bool find(string s);
  void print(void); };

                              void oldinsert(StringTree * & t, string s)
                              { if (t==NULL)
                                  t = new StringTree(s);
                                else if (s <= t->data)
                                  oldinsert(t->left, s);
                                else
                                  oldinsert(t->right, s); }

void StringTree::insert(string s)
{ if (this==NULL)
    * this = StringTree(s);
  else if (s <= data)
    left->insert(s);
  else
    right->insert(s); }