#include <fstream>
#include <cstring>

using namespace std;

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

class Node{
public:
    int nrap, nrc;
    Node *fii[26];

    Node(){

    for(int i = 0; i < 26; i++)
        fii[i] = NULL;
    nrap = nrc = 0;

    }
};

Node* insert_trie(Node* node, char *s)
{
    if(node == NULL) node = new Node;

    node-> nrap++;

    if(s[0] == '\0')
        node-> nrc++;
    else
        node-> fii[s[0] - 'a'] = insert_trie(node-> fii[s[0] - 'a'], s + 1);

    return node;
}

Node* delete_trie(Node* node, char *s)
{
    node-> nrap--;

    if(s[0] == '\0')
        node-> nrc--;
    else
        node-> fii[s[0] - 'a'] = delete_trie(node-> fii[s[0] - 'a'], s + 1);

    if(node-> nrap == 0)
        {
            delete node;
            node = NULL;
        }

    return node;
}

int nrap(Node* node, char *s)
{
    if(node == NULL)
        return 0;

    if(*s == '\0')
        return node-> nrc;

    return nrap(node-> fii[s[0] - 'a'], s + 1);
}

int bestPref(Node* node, char *s)
{
    if(node == NULL)
        return -1;

    if(*s == '\0')
        return 0;

    return 1 + bestPref(node-> fii[s[0] - 'a'], s + 1);
}

int main()
{
    Node* trie = NULL;
    char c, s[21];

    while(fin >> c)
    {
        fin >> s;

        if(c == '0') trie = insert_trie(trie, s);
        else if(c == '1') trie = delete_trie(trie, s);
        else if(c == '2') fout << nrap(trie, s) << '\n';
        else fout << bestPref(trie, s) << '\n';
    }

    return 0;
}