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

#define M 999997/* 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; }
int h2(int key){ return key%(M-1)+1; }

int find(char str[]){
 int i=0;
 int j;
 long long key;
 key = getKey(str);
 while(1){
   j=(h1(key)+i*h2(key))%M;
   if( H[j][0] == '\0' || i == M ) return 0;
   if( strcmp(H[j],str) == 0 ) return 1;
   else i++;
 }
}

int insert(char str[]){
 int i = 0;
 int j;
 long long key;
 key = getKey(str);
 while( i != M ){
   j = (h1(key)+i*h2(key))%M;
   if( H[i][0] == '\0' ){
     strcpy(H[j],str);
     return 0;
   }
   else i++;
 }
}

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