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

#define M 1000003
#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 1 + (key % (M-1)); }

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

void insert(char str[]){
    long long key,i = 0,h;
    key = getkey(str);
    while(i < M){
      h = (h1(key) + i * h2(key)) % M;
      if(H[h][0] == '\0'){
        strcpy(H[h],str);
        break;
      }
      i++;
    }
}

int main(){
    int i, n, h, k = 0;
    char str[L], com[9], display[500000][4];
    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)){
		      strcpy(display[k],"yes");
          k++;
	    } else {
		      strcpy(display[k],"no");
          k++;
	    }
	}
    }

    for(i = 0;i < k;i++){
      printf("%s\n",display[i]);
    }

    return 0;
}

