#include <iostream>
#include <fstream>
#include <map>
#include <string>
using namespace std;
ifstream f("trie.in");
ofstream g("trie.out");
map<string,int> M;
map<string,int>::iterator it,IT;
int op,maxim,i,n,c,k,m;
string w,s,s2;
int main()
{
    while(!f.eof())
    {
       f>>op>>w;
       it=M.find(w);
       if (op==0)
       {
           if (it==M.end()) M.insert(make_pair(w,1));
           else it->second=it->second+1;
       }
       else if (op==1)
       {
          if (it->second==1) M.erase(w);
          else it->second=it->second-1;
       }
       else if (op==2)
       {
           if (it==M.end()) g<<0<<"\n";
           else g<<it->second<<"\n";
       }
       else
       {
            if (it!=M.end())
            {
                s=it->first;
                g<<s.length()<<"\n";
            }
            else
            {
                 s=w;
                 maxim=0;
            for(IT=M.begin();IT!=M.end();++IT)
              {
                  s2=IT->first;
                  n=s2.length()-1;
                  m=s.length()-1;
                  if (n>m) k=m;else k=n;
                  c=0;
                  for(i=0;i<=k;++i)
                   if (s[i]==s2[i]) ++c;else break;
                   if (c>maxim) maxim=c;
              }
              g<<maxim<<"\n";
        }

       }
    }
    f.close();
    g.close();
   // for(it=M.begin();it!=M.end();++it)
   // cout<<it->first<<" "<<it->second<<"\n";
    return 0;
}