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

#define M 10001
#define NIL (-1)
#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 key, n, i=0;
  key = getKey(str);
  while(1){
    n = (h1(key) + i*h2(key)) % M;
    if(H[n][0] != '\0'){
      if(strcmp(H[n],str) == 0){
	return 1;
	break;
      }
      else i++;
    }
    else{
      return 0;
      break;
    }
  }
}

int insert(char str[]){
  int key, n, i=0;
  key = getKey(str);
  while(1){
    n = (h1(key) + i*h2(key)) % M;
    if(H[n][0] != NIL){
      strcpy(H[n],str);
      break;
    }
    else 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)) printf("yes\n");
	else printf("no\n");
      }
    }   
    return 0;
}