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

#define M 1000000
#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,h;

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

int insert(char str[]){
  long long key,i,h;

  key = getKey(str);
  i=0;

    while(1){
      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;
      } 
        else{
          i++;
        }
      }
    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;
}

