struct element{
    int label;
    bool used;
};
struct bt{
    struct element elements[1000];
};
typedef struct bt *btree;
typedef int node;
 
btree InitB(int x,btree T){
     T = new bt;
     T->elements[1].label = x;
     T->elements[1].used = true;
     return T;
}
node ParentB(node n,btree T){
     if(T==NULL) return 0;
     if(n<2) return LAMBDA;
     return n/2;
}
node LeftChildB(node n,btree T){ 
     if(T->elements[2*n].used == false) return LAMBDA;
     return 2*n;
}
node RightChildB(node n,btree T){
     if(T->elements[2*n+1].used == false) return LAMBDA;
     return 2*n+1;     
}
int LabelB(node n,btree T){
     if(T==NULL) return 0;
     if(T->elements[n].used == false) return LAMBDA;
     return T->elements[n].label;
}
void ChangeLabelB(int x,node n,btree T){
     T->elements[n].label = x;
}
node RootB(btree T){
     if(T==NULL) return 0;
     if(T->elements[1].used == false) return LAMBDA;
     return 1;
}
int CreateLeftB(int x,node n,btree T){
     if(T->elements[2*n].used == true) return -1;
     T->elements[2*n].used = true;
     T->elements[2*n].label = x;
     return 0;
}
int CreateRightB(int x,node n,btree T){
     if(T->elements[2*n+1].used == true) return -1;
     T->elements[2*n+1].used = true;
     T->elements[2*n+1].label = x;
     return 0;
}
bool ExistsLeftChildB(node n,btree T){
     if(T==NULL) return LAMBDA;
     if(T->elements[n*2].used == true) return true;
     return false;
}
bool ExistsRightChildB(node n,btree T){
     if(T==NULL) return LAMBDA;
     if(T->elements[n*2+1].used == true) return true;
     return false;
}
void DeleteB(node n,btree T){
   if(ExistsLeftChildB(n,T)){
       DeleteB(LeftChildB(n,T),T);
   }
   if(ExistsRightChildB(n,T)){
       DeleteB(RightChildB(n,T),T);
   }
   T->elements[n].used = false;
}