#include <bits/stdc++.h>
#define readFast ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define fin cin
#define ll long long
#define sz(x) (int)(x).size()
#define all(v) v.begin(), v.end()
#define output(x) ((int)x && cout << "YES\n") || cout << "NO\n";
#define LSB(x) ((-x)&x)
using namespace std;

#ifdef LOCAL
#define read() ifstream fin("date.in.txt")
#else
#define read() ifstream fin("trie.in"); ofstream fout("trie.out");
#endif // LOCAL

map<string,int> fr;
map<string,int> pref;
int op;
string w;

void mark(string &s) {
    while(!s.empty()) {
        ++pref[s];
        s.pop_back();
    }
}

void deMark(string &s) {
    while(!s.empty()) {
        --pref[s];
        s.pop_back();
    }
}

void afis(int x) {
    read();
    #ifdef LOCAL
    cout << x << "\n";
    #else
    fout << x << "\n";
    #endif // LOCAL
}

int main() {
    read();

    while(fin >> op >> w) {
        if(op == 0) {
            ++fr[w];
            mark(w);
        }
        else if(op == 1) {
            --fr[w];
            deMark(w);
        }
        else if(op == 2) {
            afis(fr[w]);
        }
        else {
            int mx = 0;

            while(!w.empty()) {
                if(pref[w] != 0) {
                    mx = max(sz(w), mx);
                    //cout << sz(w) << " ";
                }
                w.pop_back();
            }
            // cout << '\n';
            afis(mx);
        }
    }

    return 0;
}  /*stuff you should look for
	* int overflow, array bounds
	* special cases (n=1?)
	* do smth instead of nothing and stay organized
	* WRITE STUFF DOWN
	* DON'T GET STUCK ON ONE APPROACH
~Benq~*/