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

#define M 0x400000 /* your task*/
#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 /* your task */; }
int h2(int key){ return /* your task */; }

int find(char str[]){

    /* your task */
    int h = 0, i;
    for (i = 0; str[i]; ++i) {
    	h = (h << 2) | (getChar(str[i]) - 1);
    }
    h &= M - 1;
    while (H[h][0] != '\0') {
    	if (H[h][0] == str[0]) {
    		return 1;
    	}
    	h = (M - 1) & (h + 1);
    }
	return 0;	
}

int insert(char str[]){

    /* your task */
    int h = 0, i;
    for (i = 0; str[i]; ++i) {
    	h = (h << 2) | (getChar(str[i]) - 1);
    }
    h &= M - 1;
    while (H[h][0] != '\0') {
    	h = (M - 1) & (h + 1);
    }
    H[h][0] = str[0];
	//strcpy(H[h], str);
	return h;
}

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;
}