#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;--i)
#define srep(i,s,t) for(int i=(int)(s);i<(int)(t);++i)
#define each(a,b) for(auto& (a): (b))
#define all(v) (v).begin(),(v).end()
#define len(v) (int)(v).size()
#define zip(v) sort(all(v)),v.erase(unique(all(v)),v.end())
#define cmx(x,y) x=max(x,y)
#define cmn(x,y) x=min(x,y)
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define sar(a,n) {cout<<#a<<":";rep(pachico,n)cout<<" "<<a[pachico];cout<<endl;}

using namespace std;

template<typename S,typename T>auto&operator<<(ostream&o,pair<S,T>p){return o<<"{"<<p.fi<<","<<p.se<<"}";}
template<typename T>auto&operator<<(ostream&o,set<T>s){for(auto&e:s)o<<e<<" ";return o;}
template<typename S,typename T,typename U>
auto&operator<<(ostream&o,priority_queue<S,T,U>q){while(!q.empty())o<<q.top()<<" ",q.pop();return o;}
template<typename K,typename T>auto&operator<<(ostream&o,map<K,T>&m){for(auto&e:m)o<<e<<" ";return o;}
template<typename T>auto&operator<<(ostream&o,vector<T>v){for(auto&e:v)o<<e<<" ";return o;}
void ashow(){cout<<endl;}template<typename T,typename...A>void ashow(T t,A...a){cout<<t<<" ";ashow(a...);}
template<typename S,typename T,typename U>
struct TRI{S fi;T se;U th;TRI(){}TRI(S f,T s,U t):fi(f),se(s),th(t){}
bool operator<(const TRI&_)const{return(fi==_.fi)?((se==_.se)?(th<_.th):(se<_.se)):(fi<_.fi);}};
template<typename S,typename T,typename U>
auto&operator<<(ostream&o,TRI<S,T,U>&t){return o<<"{"<<t.fi<<","<<t.se<<","<<t.th<<"}";}

typedef pair<int, int> P;
typedef pair<ll, ll> pll;
typedef TRI<int, int, int> tri;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<P> vp;
typedef vector<double> vd;
typedef vector<string> vs;

const int MAX_N = 100005;

template<typename T> class Treap {
private:
    struct node {
        const T key;
        const unsigned int priority;
        node *left, *right;
        node(const T& _key) : key(_key), priority(xor128()), left(nullptr), right(nullptr){}
        static unsigned int xor128(){
            static unsigned int x = 123456789, y = 362436069, z = 521288629, w = 86675123;
            unsigned int t = (x^(x<<11));
            x = y, y = z, z = w;
            return (w = (w^(w>>19))^(t^(t>>8)));
        }
    };
    void split(node *cur, const T& new_key, node*& left, node*& right){
        if(!cur){
            left = right = nullptr;
        }else if(new_key < cur->key){
            split(cur->left, new_key, left, cur->left), right = cur;
        }else{
            split(cur->right, new_key, cur->right, right), left = cur;
        }
    }
    void insert(node** cur, node *new_node){
        while(*cur){
            if((*cur)->priority < new_node->priority){
                split(*cur, new_node->key, new_node->left, new_node->right), *cur = new_node;
                return;
            }
            cur = &(new_node->key < (*cur)->key ? (*cur)->left : (*cur)->right);
        }
        *cur = new_node;
    }
    bool find(node *cur, const T& key){
        while(cur){
            if(cur->key == key) return true;
            cur = (key < cur->key ? cur->left : cur->right);
        }
        return false;
    }
    node *root;
public:
    Treap() : root(nullptr){}
    void insert(const T& key){
        node *new_node = new node(key);
        insert(&root, new_node);
    }
    bool find(const T& key){
        return find(root, key);
    }
};

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    Treap<string> tr;
    string s, t;
    rep(i,n){
        cin >> s >> t;
        if(s[0] == 'i'){
            tr.insert(t);
        }else{
            if(tr.find(t)){
                cout << "yes\n";
            }else{
                cout << "no\n";
            }
        }
    }
    return 0;
}



Measured memory_bytes: 57380