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

#define M 1046527
#define NIL (-1)
#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;
  else 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 - 1)); }

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

int insert(char str[]){
  long long key, i, h;
  key = getKey(str);
  for (i = 0;; i++){
    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;
    }
  }

  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;
}

