#include<stdio.h>
#include<string.h>
#define M 100000000
#define L 14
int getChar(char ch);
long long getKey(char str[L]);
//int h1(int key);
//int h2(int key);
int find(char str[L]);
void insert(char str[L]);
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;
  return 0;
}
/* convert a string into an integer value */
long long getKey(char str[L]){
  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 /* your task */; }
//int h2(int key){ return /* your task */; }

int find(char str[L]){
  int key;
  key=getKey(str);
  if(H[key][0]=='\0') return 0;
  else return 1;
}

void insert(char str[]){
  strcpy(H[getKey(str)],str);
}

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;
}