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

#define M 1046527/* your task*/
#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;
 else return 0;
}

/* 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;/* your task */ }
int h2(int key){ return 1+(key%(M-1));/* your task */ }

int find(char str[]){
/* your task */
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[]){
/* your task */
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;
}

