class Trie {
    struct Node {
        bool is_end = false;

        map<char, Node *> next;
    };

    Node* root = nullptr;

public:
    Trie();

    void insert(string s);

    void erase(string s);

    bool check(string s);
};

Trie::Trie() {
    root = new Node();
}

void Trie::insert(std::string s) {
    Node* cur = root;

    for (auto i : s) {
        if (!cur->next[i]) {
            cur->next[i] = new Node();
        }
        cur = cur->next[i];
    }

    cur->is_end = true;
}

void Trie::erase(string s) {
    Node* cur = root;

    for (auto i : s) {
        if (!cur->next[i]) {
            return;
        }
        cur = cur->next[i];
    }

    cur->is_end = false;
}

bool Trie::check(string s) {
    Node* cur = root;

    for (auto i : s) {
        if (!cur->next[i]) {
            return false;
        }
        cur = cur->next[i];
    }

    return cur->is_end;
}