#include <fstream>
#include <cstring>

using namespace std;

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

const int SIGMA = 26;
const int LMAX = 20;

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

    Node() {
        nrap = nrc = 0;
        memset(fii, NULL, sizeof(fii));
    }
};

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

    node-> nrap++;

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

    return node;
}

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

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

    if(node-> nrap == 0)
        node = NULL;

    return node;
}

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

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

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

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

    if(s[0] == '\0')
        return 0;

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

int main()
{
    Node* trie = NULL;

    int op;
    char s[LMAX + 5];

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

        if(op == 0)
            trie = InsertTrie(trie, s);
        else if(op == 1)
            trie = DeleteTrie(trie, s);
        else if(op == 2)
            fout << ApTrie(trie, s) << '\n';
        else
            fout << BestPref(trie, s) << '\n';
    }

    return 0;
}