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

#define M 1000000/* your task*/
#define L 14

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

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;
}

/* 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 - 1)); 
}

int find(char str[])
{

    long long i,n,k;
    k = getKey(str);
    for(i=0;;i++)
    {
      n = (h1(k)+i*h2(k))%M;
     if(strcmp(H[n],str) == 0) return 1;
     else if(strlen(H[n]) == 0) return 0;
    }
  return 0; 

}

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