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

#define M 1000001
#define L 14

char H[M][L]; /* Hash Table */
typedef long long ll;

int getChar(char ch)
{
	if (ch == 'A') return 1;
	else if (ch == 'C') return 2;
	else if (ch == 'G') return 3;
	else if (ch == 'T') return 4;
}

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[])
{
	ll key = 0, i = 0, l = 0;
	key = getKey(str);
	while (1)
	{
		l = (h1(key) + i*h2(key)) % M;
		if (strcmp(H[l], str)==0)
		{
			return 1;
		}
		else if (strlen(H[l]) == 0)
		{
			return 0;
		}
		i++;
	}
}

int insert(char str[])
{
	ll key = 0, i = 0, l = 0;
	key = getKey(str);
	while (1)
	{
		l = (h1(key) + i*h2(key)) % M;
		if (strcmp(H[l], str)==0)
		{
			return 0;
		}
		else if (strlen(H[l]) == 0)
		{
			strcpy(H[l], str);
			return 1;
		}
		i++;
	}
}

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;
}
