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

#define M 1000001
#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 key % M; }
int h2(int key){ return (key % (M-1)) + 1; }

int find(char str[]){
    long long s = getKey(str);
    int h_1 = h1(s);
    int h_2 = h2(s);
    int k, i = 0;

    while(1){
        k = (h_1 + i * h_2) % M;
        if(H[k][0] == '\0') return 0;
        else if(strcmp(H[k], str) == 0) {
            return 1;
            break;
        }
        i++;
    }
    return 0;
}

int insert(char str[]){
    long long s = getKey(str);
    int h_1 = h1(s);
    int h_2 = h2(s);
    int k, i = 0;

    while(1){
        k = (h_1 + i * h_2) % M;
        if(H[k][0] == '\0'){
            strcpy(H[k], str);
            break;
        }
        else continue;
        i++;
    }

}

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;
}