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

#define M 1000000
#define L 14

char H[M][L]; /* Hash Table */

int getChar(char);
long long getKey(char[]);
int key(int);
int key(int);
int insert(char[]);

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;
 int i,x,y,sum;

 key = getKey(str);
 x = h1(key);
 y = h2(key);

 for( i = 0 ; i < M ; i++ )
   {
     sum = (x+i*y)%M;
     if( strcmp(H[sum],str) == 0 )
       return 1;
     else if( H[sum][0] == '\0' )
         return 0;
   }
 return 0;
}

int insert(char str[]){
 long long key;
 int i,x,y,sum;

 key = getKey(str);
 x = h1(key);
 y = h2(key);

 for( i = 0 ; i < M ; i++ )
   {
     sum = (x+i*y)%M;
     if( strcmp(H[sum],str) == 0 )
       return 1;
     else if( H[sum][0] == '\0' )
       {
	 strcpy(H[sum],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;
}