import java.io.*;
import java.util.Arrays;
import java.util.Objects;

class TrieNode {
    private TrieNode[] next = new TrieNode[26];
    private int count = 0;

    boolean hasNext() {
        return Arrays.stream(next).anyMatch(Objects::nonNull);
    }

    boolean isPrefix() {
        return count > 0 || Arrays.stream(next).filter(Objects::nonNull).count() > 1;
    }

    TrieNode insert(char c, boolean isLastIndex) {
        int index = c - 'a';

        if(next[index] == null) {
            TrieNode newNode = new TrieNode();
            next[index] = newNode;
        }

        if(isLastIndex)
            ++next[index].count;

        return next[index];
    }

    boolean delete(String word, int charIndex) {
        int index = word.charAt(charIndex) - 'a';

        if(next[index] == null)
            return false;

        if(charIndex == word.length() - 1) {
            if(--next[index].count == 0) {
                next[index] = null;
                return true;
            }

            return false;
        } else {
            if(next[index].delete(word, charIndex + 1) && next[index].count == 0 && !next[index].hasNext()) {
                next[index] = null;
                return true;
            }

            return false;
        }
    }

    int count(String word, int charIndex) {
        int index = word.charAt(charIndex) - 'a';

        if(next[index] == null)
            return 0;

        if(charIndex == word.length() - 1)
            return next[index].count;
        else
            return next[index].count(word, charIndex + 1);
    }

    int prefix(String word, int charIndex) {
        int index = word.charAt(charIndex) - 'a';

        if(charIndex == word.length() - 1)
            return next[index].hasNext() ? charIndex + 1 : 0;
        else
            return Math.max(
                    isPrefix() ? charIndex : 0,
                    next[index] == null ? (hasNext() ? charIndex : 0) : next[index].prefix(word, charIndex + 1));
    }

    void print(int level) {
        for(int i = 0; i < 26; ++i) {
            if(next[i] != null) {
                System.out.printf("Level %d edge %s count %d\n", level, (char)('a' + i), next[i].count);
                next[i].print(level + 1);
            }
        }
    }
}

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new FileReader("trie.in"));
        BufferedWriter bw = new BufferedWriter(new FileWriter("trie.out"));

        TrieNode trieRoot = new TrieNode();

        String line;
        while((line = br.readLine()) != null) {
            String s = line.substring(2);
            switch (line.charAt(0)) {
                case '0':
                    insert(trieRoot, s, 0);
                    break;
                case '1':
                    trieRoot.delete(s, 0);
                    break;
                case '2':
                    bw.write(trieRoot.count(s, 0) + "\n");
                    break;
                case '3':
                    bw.write(trieRoot.prefix(s, 0) + "\n");
                    break;
            }
        }

        br.close();
        bw.close();
    }

    private static void insert(TrieNode node, String word, int index) {
        if(index < word.length())
            insert(node.insert(word.charAt(index), index == word.length() - 1), word, index + 1);
    }
}