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

#define M 1046527/* your task*/
#define L 14
#define X 7

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 0;
}

/* convert a string into an integer value */
int getKey(char str[]){
  int 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/* your task */;
}

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

int find(char str[]){
  int i = 0;
  int h = 0;
  int got = 0, got1 = 0, got2 = 0;

  got = getKey(str);
  got1 = h1(got);
  got2 = h2(got);
  while(1){
    h = (got1 + i * got2) % M;
    if(strcmp(str, H[h]) == 0){    
      return 1;
    }
    else if(strlen(H[h]) == 0)return 0;
    i++;
  }
}

void insert(char str[]){
  int i = 0;
  int h = 0;
  int got = 0, got1 = 0, got2 = 0;

  got = getKey(str);
  got1 = h1(got);
  got2 = h2(got);
  while(1){
    h = (got1 + i * got2) % M;
    if(strcmp(H[h],str) == 0)break;
    else if(H[h][0] == '\0'){
      strcpy(H[h],str);
      break;
    }
    i++;
  }
}

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) == 1){
		printf("yes\n");
	    } else {
		printf("no\n");
	    }
	}
    }

    return 0;
}

