/*
 *    Author:
 *        Indestinee
 *    Date:
 *        2016/05/14
 */
#include <map>
#include <set>
#include <cmath>
#include <cstdio>
#include <string>
#include <vector>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
class node{
    
public:
    node(){for(int i=0;i<26;i++){a[i]=NULL;cnt[i] =0;}}
    int cnt[26];
    node *a[26];
};

int n;
char a[20], b[40];
void add( node * now , int id , int len ){
    if( id == len )
        return;
    int x = b[id] - 'a';
    if( now->a[x] == NULL )
        now->a[x] = new node;
    now->cnt[x] ++;
    add( now->a[x] , id + 1 , len );
}
int kill = 0;
void del( node *now , int id , int len ){
    
    int x = b[id] - 'a';
    if( now->a[x] == NULL )
        return;
    if( id == len - 1 ){
        now->a[x] = NULL;
        kill = now->cnt[x];
    }else
        del( now->a[x] , id + 1 , len );
    now->cnt[x] -= kill;
    if( now->cnt[x] == 0 )
        now->a[x] = NULL;
}

bool ser( node *now , int id , int len ){
    int x = b[id] - 'a';
    if( now->a[x] == NULL )
        return false;
    if( id == len - 1 )
        return true;
    return ser( now->a[x] , id + 1 , len );
}
int main(){
//    freopen( "C.in"  , "r" , stdin  );
//    freopen( "C.out" , "w" , stdout );
    scanf( "%d" , &n );
    node *st = new node;
    while( n -- ){
        kill = 0;
        scanf( "%s%s" , a , b );
        if( a[0] == 'i' ){
            add( st , 0 , strlen( b ) );
        }else if( a[0] == 'd' ){
            del( st , 0 , strlen( b ) );
        }else if( a[0] == 's' ){
            puts( ser( st , 0 , strlen( b ) ) ? "Yes" : "No" );
        }
    }
    return 0;
}