void AddVertex(int data, vertex *&root)
{
 vertex **p;
 p=&root;
 while((*p)!=NULL)
 {
  if(data<(*p)->data) p=&((*p)->left);
  else
   if(data>(*p)->data) p=&((*p)->right);
   else
    if(data==(*p)->data) break;
 }
 if((*p)==NULL)
 {
  *p=new vertex;
  if((*p)==NULL)   
  {
   printf("Error 0x42! Not enought memory!\n");
  }
  (*p)->data=data;
  (*p)->right=NULL;
  (*p)->left=NULL;
  
 }
}