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

#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); //?????????????????\???scanf????????¨

        if( com[0] == 'i' ){
            insert(str);
        }else{
            if( find(str) ){
                puts("yes");
            }else{
                puts("no");
            }
        }
    }
    return 0;
}