#include <stdio.h>
#include <stdlib.h>
#define NODE_NUM 100000
struct node_t {
    int key;
    struct node_t *next;
};
typedef struct node_t Node;
 
Node *insert_value(Node *node, int value) {
    Node *p;
 
    p = malloc(sizeof(Node));
    p->key = value;
    p->next = node;
    return p;
}
 
int find_value(Node *node, int value) {
    Node *p;
 
    for (p = node; p != NULL; p = p->next) {
        if (p->key == value)
            return 1;
    }
    return 0;
}
 
int get_key(char str[15]) {
    static int code['T'+1] = {['A']=1, ['C']=2, ['G']=3, ['T']=4};
    int i, s = 0, p = 1;
 
    for (i = 0; str[i] != '\0'; i++) {
        s += p * code[(int)str[i]];
        p *= 5;
    }
    return s;
}
 
int main(void) {
    Node *nodes[NODE_NUM] = {0};
    int num_cmd, key, index;
    char cmd[15], str[15];
 
    scanf("%d ", &num_cmd);
    while (num_cmd--) {
        scanf("%s %s", cmd, str);
        key = get_key(str);
        index = key % NODE_NUM;
        if (cmd[0] == 'i') {
            nodes[index] = insert_value(nodes[index], key);
        } else {
            if (find_value(nodes[index], key)) {
                puts("yes");
            } else {
                puts("no");
            }
        }
    }
    return 0;
}