/*
 * Dictionary.c
 *
 *  Created on: 2015/02/16
 */
#include<stdio.h>
#include<string.h>

#define M 1000213

void insert(char*);
int find(char*);
int get_key(char*);
int get_keycode(char);
int get_hash_num(int,int);

char hash[M][13]={"\0"};

int main(void){
	int n;
	int i;
	char str[13],input[7];

	scanf("%d",&n);

	for(i=0;i<n;i++){
		scanf("%s %s",input,str);

		if(input[0]=='i') insert(str);

		if(input[0]=='f'){
			if(find(str)==1) printf("yes\n");
			else printf("no\n");
		}
	}

	return 0;
}

void insert(char *str){
	int i=0,hash_num,data;

	data=get_key(str);

	while(1){
		hash_num=get_hash_num(data,i);
		if(strcmp(hash[hash_num],"\0")==0){
			strcpy(hash[hash_num],str);
			break;
		}
		i++;
	}

}

int find(char *str){
	int data,hash_num,i=0;

	data=get_key(str);

	while(1){
		hash_num=get_hash_num(data,i);
		if(strcmp(hash[hash_num],"\0")==0) return 0;
		if(strcmp(hash[hash_num],str)==0) return 1;
		i++;
	}
}

int get_key(char *str){
	int data=0,cnt=0,p=1;

	while(str[cnt]!='\0'){
		data+=p*get_keycode(str[cnt]);
		p*=5;
		cnt++;
	}

	return data;
}

int get_keycode(char work){
	switch(work){
	case 'A':
		return 1;
	case 'C':
		return 2;
	case 'G':
		return 3;
	case 'T':
		return 4;
	}
}

int get_hash_num(int data,int i){
	return ((data%M)+i*(data%(M-1)+1))%M;
}