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

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

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

typedef struct {
  char order[6];
  char word[12];
} Orders;

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; /* your task */; }
int h2(int key){ return 1 + (key % (M - 1)); /* your task */; }

int find(char str[]){

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

int insert(char str[]){

    /* your task */
  long long key,i = 0,h;
  key = getKey(str);
  while(1){
    h = (h1(key) + i * h2(key)) % M;
    if(strcmp(H[h],str) == 0) return 1;
    else if(strlen(H[h]) == 0){
      strcpy(H[h],str);
      return 0;
    }
    i++;
  }

}

int main(){
  int i, n, h;
  Orders *bb;
  for ( i = 0; i < M; i++ ) H[i][0] = '\0';
    
  scanf("%d", &n);
  bb = (Orders *)malloc(n * sizeof(Orders));
  for(i = 0;i < n;i++){
    scanf("%s %s",bb[i].order,bb[i].word);

    if(bb[i].order[0] == 'i'){
      insert(bb[i].word);
    }
    else {
      if(find(bb[i].word) == 1) printf("yes\n");
      else printf("no\n");
    }
  }
  free(bb);
  return 0;
}

