#define M 1046527
#define NIL (-1)
#define L 14

char H[M][L];

//?????????????????°????????????
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;
    else return 0;
}

//????????????????????°??????????????????key???????????????
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, i, h;
    key = getKey(str);
    for ( i = 0;; i++) {
        h = (h1(key) + i * h2(key)) % M;
        if ( strcmp(H[h], str) == 0) return 1;
        else if ( strlen(H[h]) == 0) return 0;
        
    }
    return 0;
}

int insert(char str[]) 
{
    long long key, i, h;
    key = getKey(str); //??????????????°????????????
    for ( i = 0; ; i++) {
        h = h1((key) + i * h2(key)) % M;
        if ( strcmp(H[h], str) == 0) return 1;
        else if ( strlen(H[h]) == 0) {
            strcpy(H[h], 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;
    
}