#include <fstream>
#include <algorithm>
#include <vector>
#include <cstring>
using namespace std;

ifstream cin("trie.in");
ofstream cout("trie.out");

const int ALPHABET_SIZE = 26;

struct TrieNode
{
    TrieNode *children[26];
    int word_endings;
    TrieNode()
    {
        for (int i = 0; i < ALPHABET_SIZE; i++)
            this->children[i] = nullptr;
        this->word_endings = 0;
    }
};

void insert_word(TrieNode *current, char word[])
{
    for (int i = 0; word[i] != 0; i++)
    {
        if (current->children[word[i] - 'a'] == nullptr)
        {
            current->children[word[i] - 'a'] = new TrieNode();
        }
        current = current->children[word[i] - 'a'];
    }
    current->word_endings++;
}

int word_lookup(TrieNode *current, char word[])
{
    for (int i = 0; word[i] != 0; i++)
    {
        if (current->children[word[i] - 'a'] == nullptr)
            return -1;
        current = current->children[word[i] - 'a'];
    }
    return current->word_endings;
}

bool has_children(TrieNode *current)
{
    for (int i = 0; i < ALPHABET_SIZE; i++)
        if (current->children[i] != nullptr)
            return 1;
    return 0;
}

void delete_word(TrieNode *&current, char word[], int height = 0)
{
    if (strlen(word) == height)
    {
        if (current->word_endings >= 1)
            current->word_endings--;
        if (current->word_endings == 0 && !has_children(current))
        {
            delete current;
            current = nullptr;
            return;
        }
    }
    else if (current->children[word[height] - 'a'] != nullptr)
    {
        delete_word(current->children[word[height] - 'a'], word, height + 1);
    }
    if (!has_children(current) && current->word_endings == 0)
    {
        delete current;
        current = nullptr;
    }
}

int longest_common_prefix(TrieNode *current, char word[])
{
    int i;
    for (i = 0; word[i] != 0; i++)
    {
        if (current->children[word[i] - 'a'] != nullptr)
        {
            current = current->children[word[i] - 'a'];
        }
        else
            return i;
    }
    return i;
}


int main()
{
    int op;
    TrieNode *root = new TrieNode();
    char s[100];
    while (cin >> op >> s)
    {
        if (op == 0)
        {
            insert_word(root, s);
        }
        else if (op == 1)
        {
            delete_word(root, s);
        }
        else if (op == 2)
        {
            cout << word_lookup(root, s) << '\n';
        }
        else if (op == 3)
        {
            cout << longest_common_prefix(root, s) << '\n';
        }
    }

    return 0;
}