#include<stdio.h>
#include<string.h>
#define M 1000000
#define NTL (-1)
#define L 14
 
char H[M][L]; /* Hash Table */
int count=0,k=0;
long long search[M];
 
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 getKey(H[key]); }
	int h2(int key){ return getKey(H[key]); }
 
int find(char str[]){
  int i,j;
  i=0;
  while(i!=M){
     
 
  	 if( strcmp(H[i],str)==0) return 1;
  	//if(H[i][0]==str[0]){
  		//if(search[i]==getKey(str) ) return 1;     
  	//}
  	else i++;
     
  }
  return NTL;
   
}
 
int insert(char str[]){
  while(k!=M){   
    if(H[k][0]=='\0'){     
      strcpy(H[k],str);
    	//search[k]=h1(k);
      k++;
    	return 1;
}
 
 
    else k++;
  }
  return NTL;
}
 
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;
}