#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;
}
 
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;  
  }
  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)==1){
        printf("yes\n");
        } else {
        printf("no\n");
        }
    }
    }
 
    return 0;
}