import java.util.Iterator;
import java.util.LinkedList;
import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        LinkedList<String>[] ll = new LinkedList[26];
        for(int x = 0;x<26;x++)ll[x] = new LinkedList<String>();
        Scanner sn = new Scanner(System.in);
        int n = sn.nextInt();
        while((n--)!=0){
            String s1 = sn.next(),s2 = sn.next();
            if(s1.equals("insert")){
                ll[s2.charAt(0)-'a'].offerFirst(s2);
            }else if(s1.equals("delete")){
                int top = s2.charAt(0)-'a';
                for(Iterator<String> it = ll[top].iterator();it.hasNext();){
                    if(it.next().startsWith(s2)){
                        it.remove();
                    }
                }
            }else{
                int top = s2.charAt(0)-'a';
                boolean p = true;
                for(Iterator<String> it = ll[top].iterator();it.hasNext();){
                    if(it.next().startsWith(s2)){
                        p=false;
                        System.out.println("Yes");break;
                    }
                }
                if(p)System.out.println("No");
            }
        }
        sn.close();
    }
}