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

#define M 1000000
#define L 14

char H[M][L];

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[]){
    /* your task */
  
  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 ) {
      
     return 0;   
    }
  }
  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)){
		printf("yes\n");
	    } else {
		printf("no\n");
	    }
	}
    }
    return 0;
}