#include <fstream>
#include <string>

using namespace std;
class Node {
    public:
        Node* children[26];
        int value = 0;
        Node() {
            for (int i = 0; i <= 26; i++) {
                children[i] = 0;
            }
        }
};

class Trie {

    private:
        Node* locate(string word) {
            Node* current = &root;
            for (int i = 0; i < word.length(); i++) {
                if (!current->children[word.at(i) - 97]) {
                    current->children[word.at(i) - 97] = new Node();
                }
                current = current->children[word.at(i) - 97];
            }
            return current;
        }
        
        bool isPrefix(Node* node) {
            if (!node)
                return false;
            for (int i = 0; i <= 26; i++) {
                if (node->children[i] && node->children[i]->value > 0) {
                    return true;
                }
                if (this->isPrefix(node->children[i]))
                    return true;
            }
            return false;
        }
    public:
        Node root;

        void add(string word) {
            Node* current = locate(word);
            current->value++;
        }

        void remove(string word) {
            Node* current = locate(word);
            if (current->value > 0) {
                current->value--;
            }
        }
        
        int count(string word) {
            Node* current = locate(word);
            return current->value;
        }
        
        int longest_prefix(string word) {
            for ( int i = word.size(); i >= 0; i--) {
                string prefix = word.substr(0, i);
                Node * node = this->locate(prefix);
                if (this->isPrefix(node)) {
                    return i;
                }
            }
            return 0;
        }

};

int main()
{
    ifstream fin("trie.in");
    ofstream fout("trie.out");

    Trie words;
    string word;
    int op = -3;
    while (fin>>op>>word) {
        if (op == 0) {
            words.add(word);
        } else if (op == 1) {
            words.remove(word);            
        } else if (op == 2) {
            fout<<words.count(word)<<endl;
        } else if ( op == 3) {
            fout<<words.longest_prefix(word)<<endl;
        }
    }

    return 0;
}