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

#define M 1000000
#define NTL (-1)
#define L 14

char H[M][L]; /* Hash Table */
int count=0;

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; }
//int h2(int key){ return key; }

int find(char str[]){
  int i;
  for(i=0; i<M ; i++){

    if(str[i][0]=='A'){
      if( strcmp(str,H[i])==0) return 1;}
    else if(str[i][0]=='C'){
      if( strcmp(str,H[i])==0) return 1;}

    else if(str[i][0]=='G'){
      if( strcmp(str,H[i])==0) return 1;}

    else if(str[i][0]=='T'){
      if( strcmp(str,H[i])==0) return 1;}



  }
   
  return NTL;

}

int insert(char str[]){

  strcpy(H[count],str);
  


count++;
  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)==1){
		printf("yes\n");
	    } else {
		printf("no\n");
	    }
	}
    }

    return 0;
}