/* 
 * File:   main.c
 * Author: s1252007
 *
 * Created on June 26, 2018, 12:02 PM
 */

#include <stdio.h>
#include <stdlib.h>
#define M 5000000/* 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 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, n = 0,sum;
    sum = getKey(str);
    while(i < M)
    {
        k = (h1(sum) + i * h2(sum)) % M;
        if(H[k][0]=='\0') break;
        if(strcmp(H[k],str)==0)
        {
            n=1;
            break;
        }
        i++;
    }
    return n;
}

int insert(char str[])
{
    int sum, i = 0, k; 
    sum = getKey(str);
    while(i < M)
    {
        k = (h1(sum) + i * h2(sum)) % M;
        if(H[k][0]=='\0')
        {
            strcpy(H[k],str);
            break;
        }
        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;
}


