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

#define M 1000213
#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;
}

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

int find(char str[]){
        long long key, i = 0, j;
        key = getKey(str);

        while(1){
                j = (h1(key) + i * h2(key)) % M;
                if(strcmp(H[j], str) == 0)return 1;
                else if(strlen(H[j]) == 0)return 0;
                i++;
        }
}

int insert(char str[]){
        long long key, i = 0, j;
        key = getKey(str);

        while(1){
                j = (h1(key) + i * h2(key)) % M;
                if(H[j][0] == '\0'){
                        strcpy(H[j], str);
                        break;
                }else i = i+1;
        }
        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;
}

