bool Insert(const K& key, const V& value) {
    std::lock_guard<std::mutex> lg(mutexes_[hash_(key) % table_.size() % mutexes_.size()]);
    size_t bucket_id = hash_(key) % table_.size();
    for (auto& [k, v] : table_[bucket_id]) {
        if (k == key) {
            return false;
        }
    }
    table_[bucket_id].emplace_back(key, value);
    size_.store(size_.load() + 1);
    return true;
}