#include<stdio.h>
#include<string.h>

#define M 1000000//M種類の単語入れられる /* your task*/
#define L 14//１単語12文字まで+\0

char H[M][L]; /* Hash Table */

int getChar(char ch) { //文字(列)を整数値に変換します
	if ( ch == 'A') return 1;
	else if ( ch == 'C') return 2;
	else if ( ch == 'G') return 3;
	else if ( ch == 'T') return 4;
}

/* convert a string into an integer value *///文字列を整数値に変換します
long long getKey(char str[]) {
	long long sum = 0, p = 1, i;
	for ( i = 0; i < strlen(str); i++ ) {
		sum += p*(getChar(str[i]));
		p *= 5;
	}
	return sum;//0*1+0*5+0*25
}

int h1(int key) {
	return key%M; /* your task */;
}
int h2(int key) {
	return 1+(key%(M-1));/* your task */;
}

int find(char str[]) {

	/* your task */
	long long key, h;
	key=getKey(str);
	for(int i=0; ; i++){
		h = (h1(key)+i * h2(key)) %M;
		if(strcmp(H[h], str)==0)return 1;
		else if(strlen(H[h])==0)return 0;
	}
	return 0;
}

int insert(char str[]) {
	/* your task */
	long long key, h;
	key=getKey(str);
	for(int i=0; ; i++){
		h = (h1(key)+i * h2(key)) %M;
		if(strcmp(H[h],str)==0) return 1;
		else if(strlen(H[h])==0){
			strcpy(H[h],str);
			return 0;
		}
	}
	return 0;
}

int main() {
	int i, n, h;
	char str[L], com[9];
	for ( i = 0; i < M; i++ ) H[i][0] = '\0';

	scanf("%d", &n);

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

		if ( com[0] == 'i' ) {
			insert(str);
		} else {
			if (find(str)) {
				printf("yes\n");
			} else {
				printf("no\n");
			}
		}
	}

	return 0;
}
