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

#define M 1000033/* your task*/
#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;
}

/* 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 h(int key,int i){ return (h1(key) + i*h2(key))%M/* your task */; }
int h1(int key){ return key%M/* your task */; }
int h2(int key){ return 1+key%(M - 1)/* your task */; }

int find(char str[]){
  int i=0,k=getKey(str),m=h(k,i);

  while(H[m][0] != '\0'){
   
    if(strcmp(str, H[m])==0){
  
  return 1;
    }
    i++;
    m=h(k,i);
  }
 return 11;
                 /* your task */

}

int insert(char str[]){

  int i=0,k=getKey(str),m;
  while(1){
    m=h(k,i);
    if( H[m][0] == '\0'){
      strcpy(H[m],str);
      return 7;
    }
    i++;
  }

/* your task */
  
}

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;
}