#include <iostream>
#include <exception>
#include <memory>


struct Node {
  Node(int value): value(value) {}
  int value;
  std::shared_ptr<Node> left = nullptr;
  std::shared_ptr<Node> right = nullptr;
};


struct BinarySearchTree {
  std::shared_ptr<Node> root_node = nullptr;
};


void add(int value, std::shared_ptr<Node> &current) {
  if (current == nullptr) {
    Node new_node(value);
    current = std::make_shared<Node>(new_node);
    return;
  }

  if (value < current->value)
    add(value, current->left);

  if (value > current->value)
    add(value, current->right);

  if (value == current->value)
    throw std::exception();
}


int get(int value, std::shared_ptr<Node> &current) {
  if (value < current->value)
    get(value, current->left);

  if (value > current->value)
    get(value, current->right);

  return current->value;
}


int main() {
  BinarySearchTree test;
  add(8, test.root_node);
  add(6, test.root_node);
  add(3, test.root_node);

  std::cout << get(8, test.root_node) << std::endl;

  return 0;
}