typedef struct TreeNodeStruct { 
     struct TreeNodeStruct *leftPtr;    // pointer to left subtree
     int data;                                     // node value
     struct TreeNodeStruct *rightPtr; // pointer to right subtree
} TreeNode;

typedef TreeNode * Tree;

void treeInsert( Tree * t, int value );
void treeInsertIter( Tree * t, int value );

void inOrder( Tree t );
void preOrder( Tree t );
void postOrder( Tree t );

void treeDelete( Tree * t, int value );