/**
 *
 *  Trie is an efficient information reTRIEval Data Structure.
 *
 */
#include <fstream>
#include <iostream>
#include <string>
#define FIN "trie.in"
#define FOUT "trie.out"
#define ALPHABET_SIZE 26

using namespace std;

struct Trie {
 
       int words,

           prefixes;
 
       Trie *sons[ ALPHABET_SIZE ];

       Trie() {

           words = prefixes = 0; 

           for(int i = 0; i < ALPHABET_SIZE; i++) sons[ i ] = NULL; 
       }
};

Trie *T = new Trie();

void add_word(struct Trie *node, char *s) {

     if(*s == 0) { 
 
         node->words++; 

         return;
     }

     if(node->sons[ *s - 'a'] == NULL) {

        node->sons[ *s - 'a'] = new Trie;
 
        node->prefixes++; 
     }

     add_word(node->sons[*s - 'a'], s + 1);      
};

bool delete_word(Trie *node, char *s) {

     if(*s == 0) node->words--;

     else {

          if(delete_word(node->sons[*s - 'a'], s + 1)) {

             node->prefixes--;

             node->sons[*s - 'a'] = NULL;
          }
     }  

     if(node->prefixes == 0 && node->words == 0 && node != T) {

        delete node;

        return 1;    
     }

     return 0;  
};

int count_words(Trie *node, char *s) {

     if(*s == 0) return node->words; 

     if(node->sons[ *s - 'a'] == NULL) return 0;

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

int longest_common_prefix(Trie *node, char *s, int prefix) {

     if(*s == 0) return prefix; 

     if( node->sons[ *s - 'a'] != NULL ) return longest_common_prefix( node->sons[*s - 'a'], s + 1, prefix + 1 );

     return prefix; 
};

int main() {

    int type; 

    char str[ ALPHABET_SIZE ];

    ifstream fin( FIN );

    ofstream fout( FOUT );

    struct Trie *T = new struct Trie();

    while( fin>>type>>str ) {

           switch( type ) {

                   case 0: add_word(T, str);
                   break; 

                   case 1: delete_word(T, str);
                   break; 

                   case 2: fout<<count_words(T, str)<<"\n";
                   break; 

                   case 3: fout<<longest_common_prefix(T, str, 0)<<"\n";
                   break; 
           }
    }

    fin.close();

    fout.close();

    return(0); 
};