#include<stdio.h>
#include<string.h>
#define M 1000033
#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 if ( ch == 'T') return 4;
  else return -1;
}

/* 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;
  }
  //cout<<str<<" "<<sum<<endl;
  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[]){
  int key=getKey(str),i=0;
  while(1){
    int idx=h3(key,i);
    if(H[idx][0]=='\0')return -1;
    if(strcmp(str,H[idx])==0)return 1; 
    i++;
  }
}
void insert(char str[]){
  int key=getKey(str),i=0;
  int idx=0;
  while(1){
      idx=h3(key,i);
      if(H[idx][0]=='\0')break;
      i++;
  }
  strcpy(H[idx],str);
}

int main(){
  int i, h,n;
  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 {
	printf("no\n");
      }
    }
  }
  return 0;
}

