HashTable

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

using namespace std;

int Hash(const string& key) {
  return key.empty() ? 0 : key.back();
}

class HashTable {
 public:
  HashTable() : table_(8) {}
  bool Add(const string& key) {
    int h = Hash(key) % table_.size();
    auto& v = table_[h];
    auto it = find(v.begin(), v.end(), key);
    if (it != v.end()) return false;
    v.push_back(key);
    return true;
  }
  bool Remove(const string& key) {
    int h = Hash(key) % table_.size();
    auto& v = table_[h];
    auto it = find(v.begin(), v.end(), key);
    if (it == v.end()) return false;
    v.erase(it);
    return true;
  }
  bool Has(const string& key) {
    int h = Hash(key) % table_.size();
    auto& v = table_[h];
    auto it = find(v.begin(), v.end(), key);
    return it != v.end();
  }

 private:
  vector<vector<string>> table_;
};

int main() {
  HashTable t;
  string command, key;
  while (cin >> command >> key) {
    if (command == "+") {
      cout << (t.Add(key) ? "OK" : "FAIL") << "\n";
    } else if (command == "-") {
      cout << (t.Remove(key) ? "OK" : "FAIL") << "\n";
    } else if (command == "?") {
      cout << (t.Has(key) ? "OK" : "FAIL") << "\n";
    }
  }
  return 0;
}