driver code
int main ( ) { struct Node * root = createNode ( 25 ) ; root -> left = createNode ( 20 ) ; root -> right = createNode ( 30 ) ; root -> left -> left = createNode ( 18 ) ; root -> left -> right = createNode ( 22 ) ; root -> right -> left = createNode ( 24 ) ; root -> right -> right = createNode ( 32 ) ; int N = 6 ;