#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define M 1046527  //設定為素數避免求模運算無法出現下標的情況
#define NLL (-1)
#define L 14
#define ll long long int

char H[M][L];

//char 轉 int
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;
}


//str 轉int 並生成 key
ll getKey(char str[])
{
    ll 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[])
{
    ll 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[])
{
    ll 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;
}