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

#define M 1046527
#define NIL (-1)
#define L 14

char H[M] [L];

int getChar(char ch) {
if ( ch == 'A' ) return 1;
else if ( ch == 'C' ) return 2;
else if ( ch == 'G' ) return 3;
else if ( ch == 'I' ) return 4;
else return 0;
}

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;
}

int h1(int key){ return key % M; }
int h2(int key) { return 1 + (key % (M - 1)); }

int find(char str[]) {
	long long key, i, h;
	key = getKey(str);
	for (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[]) {
	long long key, i, h;
	key = getKey(str);
	for (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;
}
