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

char H[1050000][14]; 
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;
}
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 % 1050000;
}
int h2(int key){
  return 1 + (key % (1050000-1));
}
int find(char str[]){
  long long key, i, h;
  key = getKey(str);
  while(1){
    h = (h1(key) + i * h2(key)) % 1050000;
    if(strcmp(H[h], str) == 0) return 1;
    else if(strlen(H[h]) == 0) return 0;
    i++;
  }
  return 0;
}
int insert(char str[]){
  long long key, i, h;
  key = getKey(str);
  while(1){
    h = (h1(key) + i * h2(key)) % 1050000;
    if(strcmp(H[h], str) == 0) return 0;
    else if(strlen(H[h]) == 0){
      strcpy(H[h], str);
      return 0;
    }
    i++;
  }
  return 0;
}
int main(){
  int i, n, h;
  char str[14], com[9];
  for ( i = 0; i < 1050000; 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;
}