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

#define M 1046527
#define N (-1)
#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;
}

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);
  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[])
{
  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;
}

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' ){
      if (insert(str)){

      }
    } else {
      if (find(str) ){
	printf("yes\n");
      } else {
	printf("no\n");
      }
    }
  }
  return 0;
}

