include<stdio.h>

#include<string.h>



#define M 1046527

#define NIL (-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;

}



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;

}