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

#define MAX 10000

void insert(char []);
int find(char []);
int getNum(char []);

int hash[MAX];

int main(){
  int i, n;
  char str[15], cmd[10];
  
  for(i=0; i<MAX; i++) hash[i] = 0;
  scanf("%d", &n);
  for(i=0; i<n; i++){
    scanf("%s%s", cmd, str);
    if(cmd[0] == 'i') insert(str);
    else printf(find(str)?"yes\n":"no\n");
  }
  
  return 0;
}

void insert(char str[]){
  int num;
  num = getNum(str);
  hash[num] = 1;
}

int find(char str[]){
  int num;
  num = getNum(str);
  if(hash[num] == 1) return 1;
  return 0;
}

int getNum(char str[]){
  int i, sum = 0, code, x = 1;
  for(i=0; i<strlen(str); i++){
    switch(str[i]){
    case 'A':
      code = 1;
      break;
    case 'C':
      code = 2;
      break;
    case 'G':
      code = 3;
      break;
    case 'T':
      code = 4;
      break;
    }
    sum += code * x;
    x *= 5;
  }
  return sum;
}