#include <iostream>
 
using namespace std;
 
struct element {
       int label;
       int used;
};
 
struct bt {
       struct element elements [10000];
};
 
typedef struct bt *btree;
typedef int node;
 
node ParentB (node n, btree T) {
     if (n<2) {
              cout << "Greska!" << endl;
              return 0;
              }
     else if (n%2==0) return n/2;
     else return n/2-1;
}
 
node LeftChildB (node n, btree T) {
     if (T->elements[n].used==0) return 0;
     else return 2*n;
}
 
node RightChildB (node n, btree T) {
     if (T->elements[n].used==0) return 0;
     else return 2*n+1;
}
 
int LabelB (node n, btree T) {
    if (T->elements[n].used==0) {
                                cout << "Greska!" << endl;
                                return 0;
                                }
    else return T->elements[n].label;
}
 
void ChangeLabelB (int x, node n, btree T) {
     if (T->elements[n].used==0) {
                                cout << "Greska!" << endl;
                                return;
                                }
     else T->elements[n].label=x;
}
 
node RooTB (btree T) {
       if (T->elements[1].used==0) {
                                cout << "Greska!" << endl;
                                return 0;
                                }  
       else return 1;
}
 
void CreateLeftB (int x, node n, btree T) {
     if (T->elements[2*n].used==1 || T->elements[n].used==0) {
                             cout << "Greska!" << endl;
                             return;
                             }
          T->elements[2*n].used = 1;
          T->elements[2*n].label = x;
}
 
void CreateRightB (int x, node n, btree T) {
     if (T->elements[2*n+1].used==1 || T->elements[n].used==0) {
                             cout << "Greska!" << endl;
                             return;
                             }
          T->elements[2*n+1].used = 1;
          T->elements[2*n+1].label = x;
}
 
void DeleteB (node n, btree T) {
     T->elements[n].used=0;
     if (LeftChildB(n, T)) DeleteB(LeftChildB(n, T), T);  
     if (RightChildB(n, T)) DeleteB(RightChildB(n, T), T);   
}
 
btree InitB (int x, btree T) {
      T = new bt;
      for (int i=0; i<10000; i++)
          T->elements[i].used=0;
      T->elements[1].label=x;
      T->elements[1].used=1;
      return T;     
}