#include<iostream>
#include<map>
#include<string>
using namespace std;
int main(){
    int n;
    char c[207];
    string d;
    cin>>n;
    map<string,int>m;
    while(cin>>d){
    	cin.ignore();
        if(d=="add"){
            cin.getline(c,207);
            m[c]=1;
        }
        if(d=="find"){
            cin.getline(c,207);
            if(m.find(c)!=m.end())cout<<"yes"<<endl;
            else cout<<"no"<<endl;
        }
    }
    return 0;
}