#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<cctype>
#include <fstream>
#include <limits>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <cassert>
using namespace std;
int main()
{
    int n;
    set<string>se;
    set<string>::iterator it,et;
    string s,ss;
    scanf("%d",&n);
    for(int i=0; i<n; i++)
    {
        cin>>ss>>s;
        if(ss[0]=='i')
            se.insert(s);
        else if(ss[0]=='d')
        {
                it=se.lower_bound(s);
                if(it==se.end())continue;
                int slen=s.length();
                string c(*it,0,slen);
                    if(c!=s)
                     continue;
                for(et=it;;++et)
                {
                    if(et==se.end())break;
                   string c(*et,0,slen);
                    if(c!=s)
                     break;
                }
            se.erase(it,et);
        }
        else
        {
            it=se.lower_bound(s);
            if(it==se.end())
            {
                printf("No\n");
                continue;
            }
            int len=s.length();
            string c(*it,0,len);
            if(c==s)
                printf("Yes\n");
            else
                printf("No\n");
        }
    }
    return 0;
}