#include<stdio.h>
#include<string.h>
 
#define M 1000005
#define NIL (-1)
#define L 14
 
char Hash[M][L]; /* Hash Table */
 
int getChar(char ch){
    int code;
    if ( ch == 'A') code = 1;
    else if ( ch == 'C') code = 2;
    else if ( ch == 'G') code = 3;
    else if ( ch == 'T') code = 4;
 
    return code;
}
 
/* 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 (key % (M - 1)) + 1;
}
 
int find(char str[]){
    int i = 0, flag = 0;
    int h_1, h_2, h_3;
    int key = getKey(str) % M;
 
    h_1 = h1(key);
    h_2 = h2(key);
 
    while (1) {
 
        h_3 = (h_1 + i * h_2) % M;
        if(strcmp(str, Hash[h_3]) == 0) return 1;     
        if((i == M) || (Hash[h_3][0] == '\0')) return 0;
        i++;
    }
}
 
void insert(char str[]){
    int i = 0;
    int h_1, h_2, h_3;
    int key = getKey(str);
 
    h_1 = h1(key);
    h_2 = h2(key);
 
    while (1) {
        h_3 = (h_1 + i * h_2) % M;
        if (Hash[h_3][0] == '\0'){
            strcpy(Hash[h_3], str);
            break;
        }
        i++;
    }
}
 
 
int main(){
    int i, n;
    char str[L], com[9];
    for ( i = 0; i < M; i++ ) Hash[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;
}