#include <bits/stdc++.h> //Andrei Alexandru a.k.a Sho
#define ll long long
#define double long double
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#define aint(a) (a).begin(), (a).end()
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define pi pair
#define rc(s) return cout<<s,0
#define endl '\n'
#define mod 1000000007
#define PI 3.14159265359
#define INF 1000000005
#define LINF 1000000000000000005ll
#define CODE_START  ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
ll n;
string s;
struct trie{
ll cnt,f;
ll k[26];
};
vector<trie>tree;
trie idk;
void Add(ll node,ll pos){
if(tree[node].k[s[pos]-'a']==-1){
    tree.pb(idk);
    tree[node].k[s[pos]-'a']=tree.size()-1;
}
tree[tree[node].k[s[pos]-'a']].cnt++;
if(pos==s.size()-1){
    tree[tree[node].k[s[pos]-'a']].f++;
    return;
}
Add(tree[node].k[s[pos]-'a'],pos+1);
}
void Remove(ll node,ll pos){
tree[tree[node].k[s[pos]-'a']].cnt--;
if(pos==s.size()-1){
    tree[tree[node].k[s[pos]-'a']].f--;
    return;
}
Remove(tree[node].k[s[pos]-'a'],pos+1);
}
ll Cnt(ll node,ll pos){
if(tree[node].k[s[pos]-'a']==-1){
    return 0;
}
if(pos==s.size()-1){
    return tree[tree[node].k[s[pos]-'a']].f;
}
return Cnt(tree[node].k[s[pos]-'a'],pos+1);
}
ll Pref(ll node,ll pos){
if(tree[node].k[s[pos]-'a']==-1){
    return 0;
}
ll res=0;
if(tree[tree[node].k[s[pos]-'a']].cnt){
    res=pos+1;
}
if(pos==s.size()-1){
    return res;
}
return max(res,Pref(tree[node].k[s[pos]-'a'],pos+1));
}
int32_t main(){
//CODE_START;
for(ll i=0;i<26;i++)
{
    idk.k[i]=-1;
}
idk.f=0;
idk.cnt=0;
tree.pb(idk);
ifstream cin("trie.in");
ofstream cout("trie.out");
while(cin>>n>>s){
    if(n==0){
        Add(0,0);
    }else if(n==1){
    Remove(0,0);
    }else if(n==2){
    cout<<Cnt(0,0)<<endl;
    }else {
    cout<<Pref(0,0)<<endl;
}
}
}