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

#define int long long

#define M 1046527 /* your task*/
#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 (key%(M-1)); }

int find(char str[]){
  long long key = getKey(str);
  int j=h1(key);
  int j2=h2(key);
  int i=1;
  while(H[j][0]!='\0' && M >= i){
    if(!strcmp(H[j],str)) return 1;
    else {
      j=1+i*j2;
      j%=M;
      i++;
    }
  }
  return 0;
  /* your task */
  
}
int insert(char str[]){
  long long key = getKey(str);
  int j=h1(key);
  int j2=h2(key);
  int i=1;
  while(1){
    if(H[j][0]=='\0'){
      strcpy(H[j],str);
      return j;
    }
    else{
      j=1+i*j2;
      i++;
      j%=M;
    }
  }
  /* your task */
  
}

signed main(){
  int i, n;
  char str[L], com[9];
  for ( i = 0; i < M; i++ ) H[i][0] = '\0';
  
  scanf("%lld", &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;
}



