#include <iostream>

using namespace std;

struct Node {
  int data {0};
  Node* next {nullptr};
};


class MySet {
public:
  Node* head {nullptr};
  int size {0};
public:
  MySet() {  }

  void add(int value) {
    ++size;

    if (head == nullptr) {
      head = new Node;
      head->data = value;
      return;
    }

    if (head->data == value)
      throw invalid_argument("Already in set");

    Node* current = head;

    while (current->next != nullptr) {
      current = current->next;
      if (current->data == value)
        throw invalid_argument("Already in set");
    }

    current->next = new Node;
    current->next->data = value;

  }

  int getSize() {
    return size;
  }

  bool count(int value) {
    if (head == nullptr)
      return false;

    Node* current = head;

    if (current->data == value)
      return true;

    while(current->next != nullptr) {
      current = current->next;
      if (current->data == value)
       return true;
    }

    return false;
  }
};


int main() noexcept {
  MySet set;

  set.add(1);
  set.add(1);

  for (int i = 0; i < 10; ++i)
    set.add(i);

   cout << set.count(9);
}