size_t search(const std::string& source, const std::string& substring) {
    auto hasher = std::hash<std::string_view>{};
    const auto substringHash = hasher(substring);
    for (size_t index = 0; index < source.size() - substring.size() + 1; ++index) {
        auto view = std::string_view{ source };
        view.remove_prefix(index);
        view.remove_suffix(source.size() - substring.size() - index);
        if (substringHash != hasher(view)) {
            continue;
        }

        bool isSuccess = true;
        for (size_t substringIndex = 0; substringIndex < substring.size(); ++substringIndex) {
            if (source[index + substringIndex] != substring[substringIndex]) {
                isSuccess = false;
                break;
            }
        }

        if (isSuccess) {
            return index;
        }
    }

    return static_cast<size_t>(-1);
}