#include<stdio.h>
#include<string.h>
 
#define M 1000000
#define L 14
 
char H[M][L]; 
 
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;
  int i ,point;

  key = getKey(str);

  for(i = 0; ; i++) {

    point = (h1(key) + i * h2(key)) % M;

    if((strcmp(H[point], str)) == 0)
      return 1;
    
    else if(H[point][0] == '\0')
      return 0;
    
  }
  return 0;
}
  
 
int insert(char str[]){
  long long key;
  int point,i;

  key=getKey(str);

  for(i=0; ;i++){

    point = (h1(key) + i * h2(key)) % M;

    if(H[point][0]=='\0'){

      strcpy(H[point],str);

      return 0;

    }

    else if((strcmp(H[point], str)) == 0)
      return 1;
  }
 
}
 
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;
}