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

#define M 1000003
#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 == 'T') return 4;
  return 0;
}

// convert a string into an integer value
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 - 20);
}

int find(char str[])
{
	long long key;
	long long h;
	long long d;
	
	key = getKey(str);
	h = h1(key);
	d = h2(key);
	
	while(1)
	{
		if(H[h][0] == '\0')
		{
			return 0;
		}
		if(strcmp(H[h], str) == 0)
		{
			return h;
		}
		h = (h + d) % M;
	}
}

int insert(char str[])
{
	long long key;
	long long h;
	long long d;
	
	key = getKey(str);
	h = h1(key);
	d = h2(key);
	
	while(1)
	{
		if(H[h][0] == '\0')
		{
			strcpy(H[h], str);
			return h;
		}
		h = (h + d) % M;
	}
}

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;
}