#include <iostream>
#include <cmath>
#include <vector>
#include <string>
#include <map>
#include <algorithm>
#include <tuple>
#include <set>
#include <stack>
#include <queue>
#include <functional>


using namespace std;
using ll = long long;
using ull = unsigned long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
using pii = pair<int, int>;
using vpii = vector<pii>;
using pci = pair<char, int>;
using vpci = vector<pci>;
using vb = vector<bool>;
#define out(S) cout<<(S)<<endl;
#define REP(i,b) for(int i=0;i<(b);i++)
#define rREP(i,b) for(int i=(b)-1;i>=0;i--)
#define FOR(i,a,b) for(size_t i=(a);i<(b);i++)
#define rFOR(i,a,b) for(int i=(a)-1;i>=(b);i--)
#define Foreach(item,collection) for(auto item:collection)
#define mod(i) ((i) % (ll)(1e9 + 7))
ll modpow(ll i, ll j) { ll tmp = 1; while (j) { if (j % 2)tmp = mod(tmp*i); i = mod(i*i); j /= 2; }return tmp; }
#define divmod(a,b) (mod(a * modpow((ll)b,(ll)(1e9 + 5))))
#define Yes out("Yes")
#define No out("No")
#define NO out("NO")
#define YES out("YES")
#define INF 1e10;
#define ShowAll(collection) for(auto i:collection){out(i);}
#define IfOut(condition,text) if((condition)){out(text);return 0;}
#define IfeOut(condition,itext,etext) if(condition){out(itext);return 0;}else{out(etext);return 0;}
#define GetAuto(_N,vect) {cin>>_N;vect.resize(_N);REP(i,_N){cin>>vect[i];}}
#define beginend(vec) (vec).begin(),(vec).end()
#define pb(item) push_back(item)
#define removeAll(vec,deleg) auto itr=remove_if(beginend(vec),deleg);vec.erase(itr,vec.end());
void removeAt(string& s, int index) { s.erase(index, 1); }
template<typename T> void removeAt(vector<T>& v, int index) { v.erase(v.begin() + index); }
ll manhattanDistance(ll x1, ll y1, ll x2, ll y2) { return (abs(x2 - x1) + abs(y2 - y1)); }
vector<ll> sieveOfEratosthenes(int max) { ll prime; double sqrtmax = sqrt(max); vector<ll> primeVec, searchVec; FOR(i, 2, max + 1) searchVec.push_back(i); do { prime = searchVec[0]; primeVec.push_back(prime); auto itr = remove_if(beginend(searchVec), [=](ll x)->bool {return x%prime == 0; }); searchVec.erase(itr, searchVec.end()); } while (prime < sqrtmax); primeVec.reserve(primeVec.size() + searchVec.size()); primeVec.insert(primeVec.end(), beginend(searchVec)); return primeVec; }
bool isPrime(ll x) { if (x == 2) return true; if (x < 2 || x % 2 == 0) return false; ll i = 3; while (i <= sqrt(x)) { if (x%i == 0) return false; i += 2; }return true; }
vi seq(int max, int start = 0) {vi rt(max - start+1);FOR(i, start, max+1) rt[i] = i;return rt;}
template<typename T> size_t find_first_of(vector<T> v, T val) { auto itrfind = find(beginend(v), val); size_t dis = distance(v.begin(), itrfind); if (dis == v.size()) { return -1; }return dis; }
template<class T> struct Identity {typedef T type;};
template<typename T> vector<T> select(const vector<T> &v, typename Identity<function<T(const T &)>>::type ft) {vector<T> rt; for (T item : v) { rt.push_back(ft(item)); }return rt;}
template<typename T> string join(const vector<T> &v, typename Identity<function<string(const T &)>>::type ft) {string rt = "";Foreach(x, v) {rt += ft(x);}return rt;}


int main(){
	int N;
	cin >> N;
	map<string, bool> dic;
	REP(i, N) {
		string key;
		cin >> key;
		string value;
		cin >> value;
		if (key == "insert") {
			dic[value] = true;
		}
		else if(dic.count(value)!=0) {
			out("yes");
		}
		else {
			out("no");
		}
	}
	
	return 0;
}

Measured memory_bytes: 36436