LNIP2

#include <iostream>
#include <string>
#include <vector>

struct Node {
  std::string Key;
  Node* Next = nullptr;

  Node(const std::string& key) : Key(key) {}
};

class HashTable {
 public:
  // Конструктор
  HashTable(size_t initial_size) : table(initial_size, nullptr) {}

  bool Has(const std::string& key) const {
    size_t h = (key.empty() ? 0 : key[0]) % table.size();
    return HasInList(h, key);
  }
  bool Add(const std::string& key) {
    size_t h = (key.empty() ? 0 : key[0]) % table.size();
    if (HasInList(h, key)) return false;
    Node* new_node = new Node(key);
    new_node->Next = table[h];
    table[h] = new_node;
    return true;
  }
  bool Remove(const std::string& key) {
    size_t h = (key.empty() ? 0 : key[0]) % table.size();
    if (table[h] == nullptr) return false;
    if (table[h]->Key == key) {
      Node* next = table[h]->Next;
      delete table[h];
      table[h] = next;
      return true;
    }
    for (Node* current = table[h]; current->Next != nullptr; current = current->Next) {
      if (current->Next->Key == key) {
        Node* next = current->Next->Next;
        delete current->Next;
        current->Next = next;
        return true;
      }
    }
    return false;
  }

 private:
  std::vector<Node*> table;

  bool HasInList(size_t h, const std::string& key) const {
    for (Node* current = table[h]; current != nullptr; current = current->Next) {
      if (current->Key == key) return true;
    }
    return false;
  }
};

int main() {
  char command = 0;
  std::string key;

  HashTable hash_table(80);
  while (std::cin >> command >> key) {
    if (command == '+')
      std::cout << (hash_table.Add(key) ? "OK" : "FAIL") << std::endl;
    else if (command == '-')
      std::cout << (hash_table.Remove(key) ? "OK" : "FAIL") << std::endl;
    else if (command == '?')
      std::cout << (hash_table.Has(key) ? "OK" : "FAIL") << std::endl;
  }

  return 0;
}