#include <bits/stdc++.h>

using namespace std;
ifstream fin("trie.in");
ofstream fout("trie.out");
typedef struct nod{struct nod *fiu[28]; int terminal;} NOD, *TRIE;
TRIE T = NULL;
int v, maxim;
char cuv[25], *p1;
void adauga(TRIE &T, char *p)
{
    if(T == 0)
    {
        T = new NOD;
        for(int i = 0; i <= 25; ++i)T->fiu[i] = 0;
        T->terminal = 0;
        adauga(T, p);
    }
    else if(*p == '\0')T->terminal ++;
    else adauga(T->fiu[*p - 'a'], p + 1);
}
void sterge(TRIE &T, char *p)
{
    if(*(p + 1) == '\0')
    {
        T->fiu[*p - 'a'] = 0;
        T->terminal--;
    }
    else sterge(T->fiu[*p - 'a'], p + 1);
    bool ok = 1;
    for(int i = 0; i <= 25; ++i)
        if(T->fiu[i] != 0)ok = 0;
    if(ok == 1)
    {
        T = 0;
        T ->terminal = 0;
        delete(T);
    }
}
int verif(TRIE &T, char *p)
{
    if(*p == '\0')return T->terminal;
    return verif(T->fiu[*p - 'a'], p + 1);
}
int prefmax(TRIE &T, char *p)
{
    if(T->terminal!= 0 && *(p + 1)!='\0')maxim = max(maxim, p - p1);
    if(T ->terminal > 1 && *(p + 1)== '\0')maxim = max(maxim, p - p1);
    for(int i = 0; i <= 25; ++i)
        if(T->fiu[i]!= 0 && (i != *p - 'a'))
            maxim = max(maxim, p - p1);
    if(*p != '\0' && T->fiu[*p - 'a'] != 0)maxim = max(maxim,prefmax(T->fiu[*p - 'a'], p + 1));
    return maxim;
}
int main()
{
    while(fin >> v)
    {
        fin >> cuv;
        if(v == 0)
            adauga(T, cuv);
        else if(v == 1)sterge(T, cuv);
        else if(v == 2)
            fout << verif(T, cuv) << '\n';
        else
        {
            p1 = cuv;
            maxim = 0;
            fout << prefmax(T, cuv) << '\n';
        }
    }
    return 0;
}