#include<cstdio>
#include<fstream>
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<bitset>
#include<deque>
#include<queue>
#include<set>
#include<map>
#include<cmath>
#include<cstring>
#include<ctime>
#include<cstdlib>
#include<unordered_map>

#define ll long long
#define pb push_back
#define mp make_pair
#define pii pair<int,int>
#define pll pair<ll,ll>
#define all(x) (x).begin(), (x).end()
#define fi first
#define se second

using namespace std;

struct trie
{
    trie *f[26];
    int was, cnt;

    trie()
    {
        memset(f, 0, sizeof(f));
        was = cnt = 0;
    }
};

trie *root = new trie;

int op, n, l;
char s[25];

void add(trie *t, int poz)
{
    if(poz == n)
    {
        t->cnt++;
        return;
    }

    int l = s[poz] - 'a';
    if(!t->f[l]) t->f[l] = new trie;
    t->f[l]->was++;
    add(t->f[l], poz + 1);
}

void erase(trie *t, int poz)
{
    if(poz == n)
    {
        t->cnt--;
        return;
    }

    int l = s[poz] - 'a';
    t->f[l]->was--;
    erase(t->f[l], poz + 1);
}

void count(trie *t, int poz)
{
    if(poz == n)
    {
        printf("%d\n", t->cnt);
        return;
    }

    int l = s[poz] - 'a';
    if(!t->f[l] || !t->f[l]->was)
    {
        printf("0\n");
        return;
    }

    count(t->f[l], poz + 1);
}

void prefix(trie *t, int poz)
{
    if(poz == n)
    {
        printf("%d\n", n);
        return;
    }

    int l = s[poz] - 'a';
    if(!t->f[l] || !t->f[l]->was)
    {
        printf("%d\n", poz);
        return;
    }

    prefix(t->f[l], poz + 1);
}

int main()
{
    freopen("trie.in", "r", stdin);
    freopen("trie.out", "w", stdout);

    while(scanf("%d %s\n", &op, s) + 1)
    {
        n = strlen(s);

        if(op == 0) add(root, 0);
        else if(op == 1) erase(root, 0);
        else if(op == 2) count(root, 0);
        else prefix(root, 0);
    }

    return 0;
}