#include <iostream>
 
using namespace std;
 
struct element {
       int label;
       element *left, *right;
};
 
typedef element *node;
typedef element bt;
 
node ParentB (node n, bt* T) {
     if (n==T) {
               cout << "Greska!" << endl;
               return NULL;
               }
     node rod = NULL;
     if (T->left) {
                  if (T->left==n) return T;
                  else rod = ParentB (n, T->left);
                  }
     if (T->right) {
                  if (T->right==n) return T;
                  else rod = ParentB (n, T->right);
                  }
     return rod;
}
 
node LeftChildB (node n, bt* T) {
     if (n->left==NULL) return NULL;
     else return n->left;    
}
 
node RightChildB (node n, bt* T) {
     if (n->right==NULL) return NULL;
     else return n->right;    
}
 
int LabelB (node n, bt* T) {
    return n->label;   
}
 
void ChangeLabelB (int x, node n, bt* T) {
     n->label=x;
}
 
node RootB (bt* T) {
         return T;
}
 
void CreateLeftB (int x, node n, bt* T) {
        if (n->left!=NULL) {
                           cout << "Greska!" << endl;
                           return;
                           }
        node child = new element;
        n->left = child;
        child->left = NULL;
        child->right = NULL;
        child->label = x;
}
 
void CreateRightB (int x, node n, bt* T) {
     if (n->right!=NULL) {
                         cout << "Greska!" << endl;
                         return;
                         }
     node child = new element;
     n->right = child;
     child->left = NULL;
     child->right = NULL;
     child->label = x;   
}
 
void DeleteB (node n, bt* T) {
         bool rek = false;
         if (!rek) {
                   node roditelj = ParentB (n, T);
                   if (roditelj->left==n) roditelj->left=NULL;
                   if (roditelj->right==n) roditelj->right==NULL;
                   rek=true;
                   }
         if (n->left) DeleteB (n->left, T);
         if (n->right) DeleteB (n->right, T);
         delete n;
}
 
bt* InitB (labeltype x, bt* T) {
    T = new element;
    T->left = NULL;
    T->right = NULL;
    T->label = x;
    return T;   
}