#include<cstdio>
    #include<iostream>
    #include<string>
    #include<set>
    using namespace std;
    #define mp make_pair
    set<pair<string,int> > Q;
    set<pair<string,int> >::iterator it;
    int tip;
    char w[21];

    int comp(string a , string b)
    {
        int i;
        for(i = 0 ; a[i] && b[i] && a[i]==b[i] ; i++);
        return i;
    }

    int main()
    {
        freopen("trie.in" , "r" , stdin );
        freopen("trie.out" , "w" , stdout);
        while(scanf("%d %s\n" , &tip ,w)>0)
        {
            if(tip == 0)
            {
                it = Q.lower_bound(mp(w,0));
                if( it!=Q.end()&&it->first == w )
                {
                    int nr = it->second;
                    Q.erase(it);
                    Q.insert(mp(w,nr+1));
                }
                else Q.insert(mp(w,1));
            }
            if(tip == 1)
            {
                it = Q.lower_bound(mp(w,0));
                if(it->second==1)Q.erase(it);
                else{
                    int nr = it->second;
                    Q.erase(it);
                    Q.insert(mp(w,nr-1));
                }
            }
            if(tip==2)
            {
                it = Q.lower_bound(mp(w,0));
                if(it->first == w)printf("%d\n" , it->second);
                else printf("0\n");
            }
            if(tip==3)
            {
                int p1=0,p2 = 0;
                it = Q.lower_bound(mp(w,0));
                if(it!=Q.end())p1=comp(w,it->first);
                if(it != Q.begin())
                {
                    it--;
                    p2 = comp(w,it->first);
                }
                printf("%d\n" , max(p1 , p2 ));
            }
        }
        return 0;
    }