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

#define M 12 /* 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 H[key][L];/* your task */; 
}

int h2(int key)
{ 
  return H[key][L];/* your task */; 
}

int find(char str[]){
    /* your task */
  int i, j, m, k;

  i=0;

  while(1){
    j = H[k][i];
    if(str[j] == str[i]){
      return j;
    }
    else if((str[j] == NULL) || (i >= m)){  //m??£????????????
      return NULL;
    }

    else i = i + 1;

  }

}

int insert(char str[]){
    /* your task */
  int i, j, k;

  i = 0;

  while(1){
    j = H[k][i];
    if(str[j] == NULL){
      str[j] = str[i];
      return j;
    }
    else{
      i = i+1;
    }

  }

}

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;
}