#include<stdio.h>
#include<string.h>
#define M 1000000
#define L 14

char H[M][L];
int serch[M],n=0;

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;
}

int getKey(char str[]){
  int sum = 0, p = 1, i;
  for ( i = 0; i < strlen(str); i++ ){
    sum += p*(getChar(str[i]));
    p *= 5;
  }
  return sum;
}

void insert(char str[]){
  strcpy(H[n],str);
  
  serch[n]=getKey(H[n]);
  n++;
}

int find(char str[]){
  int i,sum;
  
  for(i=0;i<n;i++){
    if(serch[i]==getKey(str))return 1;
  }
  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 if(find(str)==0){
	  printf("no\n");
	}
      }
    }
  return 0;
}