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

#define M 1000
#define NIL (-1)
#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 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%L; }
int h2(int key){ return 1 + key%(L-1); }

int find(char str[]){
  long long key;
  int a1,a2,a3;
 
  key = getKey(str);
  a1 = h1(key);
  a2 = h2(key);
  a3 = a1;
  while(1){
    if(strcmp(str,H[a1])==0){
      return 1;
    }
    else{
      if(a1==a3){return 0; break;}
      a1 += a2;
      if(M<a1) a1 = a1-M;
    }
  }
}

void insert(char str[]){
  long long key;
  int a1,a2;
  int i;
  
  key = getKey(str);
  a1=h1(key);
  a2=h2(key);
  if(H[a1][0] != '\0'){
    while(1){
      a1 += a2;
      if(M<a1) a1 = a1-M;
      if(H[a1][0] != '\0') break;
    }
  }
  strcpy(H[a1],str);
}

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;
}