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

#define M 1000000
#define NIL (-1)
#define L 12
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;
}

long long getKey(char str[]) {
    int len = strlen(str);
    long long sum = 0, p = 1, i;
    for(i=0; i<len; ++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;
}
