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

#define M 1000000
#define L 12
#define NIL -1

char H[M][L]; /* Hash Table */
int n;

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 key%M; }
int h2(int key){ return 1+(key%(M-1)); }

int find(char str[])
{
  long long key;
  long long h;
  long long d;
     
  key = getKey(str);
  h = h1(key);
  d = h2(key);
     
  while(1)
    {
      if(H[h][0] == '\0')
        {
	  return 0;
        }
      if(strcmp(H[h], str) == 0)
        {
	  return h;
        }
      h = (h + d) % M;
    }
}
 
int insert(char str[])
{
  long long key;
  long long h;
  long long d;
     
  key = getKey(str);
  h = h1(key);
  d = h2(key);
     
  while(1)
    {
      if(H[h][0] == '\0')
        {
	  strcpy(H[h], str);
	  return h;
        }
      h = (h + d) % M;
    }
}


int main(){
  int i, n, h=0;
  char str[L], com[9],Ans[L][4];
  for ( i = 0; i < M; i++ ) H[i][0] = '\0';
    
  scanf("%d", &n); // n:命令の数
    
  for ( i = 0; i < n; i++ ) {
    scanf("%s %s", com, str); //com:命令 str:文字列

    if ( com[0] == 'i' ){ //insertのとき
      insert(str);
    } else {
      if (find(str)){
	printf("yes\n");
	strcpy(Ans[h],"yes");
	h++;
      } else {
	strcpy(Ans[h],"no");
	h++;
	printf("no\n");
      }
    }
  }

  for(i=0;i<h;i++){
    printf("%s\n",Ans[i]);
  }

  return 0;
}