#include<iostream>
#include<string>
using namespace std;
struct hash_table
{
    const int P = 179, Q = 2000000;
    string str[2000000];
    int nxt[2000000];
    long long hash_str(string s)
    {
        long long ans = 0;
        for (int i = 0; i < s.length(); i++)
        {
            ans = (ans*P + s[i]) % Q;
        }
        return ans;
    }
    bool check(string s)
    {
        long long hash_s = hash_str(s);
        int pos = hash_s;
        while (nxt[pos]!=pos)
        {
            if (str[pos] == s) return true;
            pos = nxt[pos];
        }
        return false;
    }
    void insert(string s)
    {
        long long hash_s = hash_str(s);
        int pos = hash_s;
        while (str[pos] != "")
        {
            if (pos + 1 < Q)
            {
                pos++;
            }
            else
            {
                pos = 0;
            }
        }
        str[pos] = s;
        if (pos != hash_s)
        {
            nxt[hash_s] = pos;
        }
    }
};
hash_table ht;
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    while (1)
    {
        char m;
        cin >> m;
        if (m == '+')
        {
            string s;
            cin >> s;
            ht.insert(s);
        }
        else if (m == '?')
        {
            string s;
            cin >> s;
            if (ht.check(s))
            {
                cout << "YES\n";
            }
            else
            {
                cout << "NO\n";
            }
        }
        else if (m == '#')
        {
            break;
        }
    }
}