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

#define M 1000010
#define L 14

char Hash[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 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 1 + (key % (M-1));
}
int h3(int key,int i){
  return (h1(key) + i * h2(key)) % M;
}

int find(char str[]){
  long long i,j,key;
  i = 0;
  key = getKey(str);
  while(1){
    j = h3(key,i);
    if(strcmp(Hash[j],str) == 0) return j;
    else if(strlen(Hash[j]) == 0 || i >= M) return 0;
    else i += 1;
  }
  return 0;
}

int insert(char str[]){
  long long i,j,key;
  i = 0;
  key = getKey(str);
  while(1){
    j = h3(key,i);
    if(strlen(Hash[j]) == 0){
      strcpy(Hash[j],str);
      return j;
    }
    else i += 1;
  }
    
  return 0;
}

int main(){
  int i, n, h;
  char str[L], com[9];
  for ( i = 0; i < M; i++ ) Hash[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;
}

