//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")

#include <bits/stdc++.h>

using namespace std;

FILE *fin = freopen("trie.in", "r", stdin);
FILE *fout = freopen("trie.out","w",stdout);

static const int MAX_LEN = 20+5;
const int TETA = 26;

struct TrieNode
{
    TrieNode *sons[TETA];
    int wordCount, wordEndingCount;

    TrieNode()
    {
        this->wordCount = this->wordEndingCount = 0;
        for(int i = 0; i < TETA; ++i)
        {
            this->sons[i] = NULL;
        }
    }
};

TrieNode *root = new TrieNode();

void Insert(TrieNode *node,char *word)
{
    node->wordCount++;
    if(*word == NULL)
    {
        node->wordEndingCount++; return;
    }
    if(node->sons[*word - 'a'] == NULL)
    {
        node->sons[*word-'a'] = new TrieNode;
    }
    Insert(node->sons[*word -'a'], word+1);
}

void Erase(TrieNode *node, char *word)
{
    node->wordCount--;
    if(*word == NULL)
    {
        node->wordEndingCount--;
        return;
    }
    Erase(node->sons[*word - 'a'], word+1);
}

int CountApparitions(TrieNode *node, char *word)
{
    if(*word == NULL)
    {
        return node->wordEndingCount;
    }
    if(node->sons[*word - 'a'] == NULL)
    {
        return 0;
    }

    return CountApparitions(node->sons[*word - 'a'], word+1);
}

int MaxCommonLength(TrieNode *node, char *word, int currentLength)
{
    if(*word == NULL || node->sons[*word - 'a'] == NULL || node->sons[*word - 'a']-> wordCount == 0)
    {
        return currentLength;
    }
    else
    {
        return MaxCommonLength(node->sons[*word - 'a'],word+1,currentLength+1);
    }
    
}

int main()
{
    ios_base::sync_with_stdio(0);
    int type;
    char word[MAX_LEN];
    while(scanf("%d%s", &type, word) == 2)
    {
        if(type == 0)
        {
            Insert(root, word);
        }
        else if(type == 1)
        {
            Erase(root,word);
        }
        else if(type == 2)
        {
            printf("%d\n",CountApparitions(root,word));
        }
        else
        {
            printf("%d\n",MaxCommonLength(root,word,0));
        }
        
    }
    return 0;
}