#include <bits/stdc++.h>
using namespace std;


struct Nod
{
public:
    int nr; /// numarul de aparitii ale unui cuvant care se termina
            /// in acest nod
    int cnt; /// numarul de cuvinte care au prefixul pana in acest nod
    Nod *leg[26]; /// leg[0]='a', ..., leg[25] = 'z'
    Nod()
    {
        nr = cnt = 0;
        for (int i = 0; i < 26; i++)
            leg[i] = NULL;
    }
};

class Trie
{
public:
    Nod *rad;
    Trie()
    {
        rad = new Nod();
    }
    /// adauga cuvantul w in trie
    void Add(string w)
    {
        Nod *p, *q;
        int j, i, len = w.length();
        p = rad;
        for (i = 0; i < len; i++)
        {
            (p->cnt)++;
            j = w[i] - 'a';
            if (p->leg[j] == NULL)
            {
                q = new Nod;
                p->leg[j] = q;
            }
            p = p->leg[j];
        }
        (p->nr)++;
        (p->cnt)++;
    }

    /// sterge cuvantul w din trie
    void Erase(string w)
    {
        Nod *p;
        int j, i, len = w.length();
        p = rad;
        for (i = 0; i < len; i++)
        {
            (p->cnt)--;
            j = w[i] - 'a';
            p = p->leg[j];
        }
        (p->nr)--;
        (p->cnt)--;
    }

    /// de cate ori apare cuvantul w in trie
    int Count(string w)
    {
        Nod *p;
        int j, i, len = w.length();
        p = rad;
        for (i = 0; i < len; i++)
        {
            j = w[i] - 'a';
            if (p->leg[j] == NULL)
                return 0;
            p = p->leg[j];
        }
        return p->nr;
    }

    /// lungimea maxima a unui prefix
    int Prefix(string w)
    {
        if (rad->cnt == 0) return 0;
        Nod *p;
        int lgmax = 0, j, i, len = w.length();
        p = rad;
        for (i = 0; i < len; i++)
        {
            j = w[i] - 'a';
            if (p->leg[j] == NULL)
                return lgmax;
            p = p->leg[j];
            if (p->cnt == 0) return lgmax;
            lgmax++;
        }
        return lgmax;
    }
};

int main()
{
    ifstream fin("trie.in");
    ofstream fout("trie.out");
    Trie A;
    int op;
    string x;
    while(fin >> op >> x)
    {
        if(op == 0) A.Add(x);
        else if(op == 1) A.Erase(x);
        else if(op == 2) fout << A.Count(x) << "\n";
        else fout << A.Prefix(x) << "\n";
    }
    fin.close();
    fout.close();
    return 0;
}