#include <cstdio>
#include <cstring>

const int SIGMA = 26;
using namespace std;

int K; char String[SIGMA];

struct trie {
    int cnt_words;
    int cnt_children;
    trie *children[SIGMA];
    
    trie () {
        cnt_words = NULL;
        cnt_children = NULL;
        
        for( int i = 0; i < SIGMA; i ++ )
            children[i] = NULL;
    }
}; trie *Root = new trie;

void insert_word( trie *Node, char *String ) {
    
    if( *String == 0 ) {
        Node -> cnt_words ++;
        return;
    }
    
    if( Node -> children[*String - 'a'] == NULL ) {
        Node -> children[*String - 'a'] = new trie;
        Node -> cnt_children ++;
    }
    
    insert_word( Node -> children[*String - 'a'], String + 1 );
    
    return;
}

int delete_word( trie *Node, char *String ) {
    
    if( *String == 0 ) Node -> cnt_words --; else
        if( delete_word( Node -> children[*String - 'a'], String + 1 ) ) {
            Node -> children[*String - 'a'] = NULL;
            Node -> cnt_children --;
        }
    
    if( Node -> cnt_words == NULL && Node -> cnt_children == NULL && Node != Root ) {
        delete Node;
        return 1;
    }
    
    return 0;
}

int count_word( trie *Node, char *String ) {
    
    if( *String == 0 )
        return Node -> cnt_words;
    
    if( Node -> children[*String - 'a'] != NULL )
        return count_word( Node -> children[*String - 'a'], String + 1 );
    
    return 0;
}

int longest_prefix( trie *Node, char *String, int prefix_length ) {
    
    if( *String == 0 )
        return prefix_length;
    
    if( Node -> children[*String - 'a'] != NULL )
        return longest_prefix( Node -> children[*String - 'a'], String + 1, prefix_length + 1 );
    
    return prefix_length;
}

int main () {
    
    freopen ("trie.in" ,"r", stdin );
    freopen ("trie.out","w", stdout);
    
    while( scanf( "%d", &K ) ) {
        scanf( "%s", String );
        
        if( String[0] == 0 )
            break;
        
        switch( K ) {
            case 0: {
                insert_word( Root, String );
                break;
            }
            case 1: {
                delete_word( Root, String );
                break;
            }
            case 2: {
                printf( "%d\n", count_word( Root, String ) );
                break;
            }
            case 3: {
                printf( "%d\n", longest_prefix( Root, String, 0 ) );
                break;
            }
        }
        
        memset( String, 0, sizeof( String ) );
    }
    
    return 0;
}