#include<stdio.h>
#include<string.h>
 
#define M 1046527
#define NTL (-1)
#define L 14
 
char H[M][L];
 
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;
}
 
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 1 + (key % (M - 1));}
 
int find(char str[]) {
long long key, i, h;
key = getKey(str);
for ( i = 0;; i++ ) {
 h = (h1(key) + i * h2(key)) % M;
 if ( strcmp(H[h],str) == 0 ) return 1;
 else if ( strlen(H[h]) == 0 ) return 0;
  }
  return 0;
}
 
int insert(char str[]) {
 long long key, i, h;
 key = getKey(str);
 for ( i = 0; ; i++ ) {
  h = (h1(key) + i * h2(key)) % M;
  if ( strcmp(H[h], str) == 0 ) return 1;
  else if ( strlen(H[h]) == 0 ) {
   strcpy(H[h], str);
   return 0;
   }
  }
return 0;
}
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;
}
