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

#define M 1000000
#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[]){
  int i = 0, j;

  j = h1(getKey(str));
  while(1) {
    if(strcmp(H[j], str) == 0) return 1;
    else {
      j += h2(getKey(str));
      if(j > M) j -= M;
    }
    i++;
    if(i == M) return 0;
  }
}

int insert(char str[]){
  int i = 0, j;

  j = h1(getKey(str));
  while (1) {
    if(H[j][0] == '\0') {
      strcpy(H[j], str);
      return j;
    }
    else if(strcmp(H[j], str) == 0) return j;
    else {
      j += h2(getKey(str));
      if(j > M) j -= M;
    }
    i++;
    if(i == M) 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;
}