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

#define M 1000003
#define L 14
#define NIL -1

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

int getChar(char);
/* convert a string into an integer value */
long long getKey(char []);
int h1(int);
int h2(int);
int find(char []);
int insert(char []);

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) != NIL){
		printf("yes\n");
	    }

        else {
		printf("no\n");
	    }
	}

    }

    return 0;
}

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[]){
int i,j;
long long key;

key = getKey(str);
i = 0;

while (1){
    j = (h1(key) + i * h2(key)) % M;

    if(strcmp(H[j],str) == 0)
    return 1;

    else if (strlen(H[j]) == 0)
    return NIL;

    else
        i = i + 1;
}

}

int insert(char str[]){
int i,j;
long long key;

key = getKey(str);

i = 0;
while (1){
    j = (h1(key) + i * h2(key)) % M;

    if (strcmp(H[j],str) == 0){
        return 1;
    }

else if (strlen(H[j]) == 0){
    strcpy(H[j],str);
    return 0;
}
    else
         i = i + 1;
}

}

