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


#define M 1000003
#define L 14 /*文字列の長さ*/

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 sum;
  int t, j;

  sum = getKey(str);
  for( j=0; j<M; j++ )
    {
      t = ((h1(sum)) + j * (h2(sum)))%M;
      if( strcmp(str,H[t]) == 0 ) return 1;
      else if( H[t][0] == '\0' )
	return 0;
    }
}

int insert(char str[])
{
  long long sum;
  int t, j;

  sum = getKey(str);
  for( j=0; j<M; j++ )
    {
      t = ((h1(sum)) + j * (h2(sum)))%M;
      if( H[t][0] == '\0' )break;
    }
  strcpy(H[t],str);	
}

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;
}

