include<iostream>

include<cstdio>

include<cstring>

include<algorithm>

using namespace std;

define M 1046527 //设置为素数避免求模运算无法出现下标的情况

define NLL (-1)

define L 14

define ll long long int

char H[M][L];

//char 转 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 转int 并生成 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;

}