#include <iostream>
#include <string>
#include <vector>
#include <map>
using namespace std;

struct node {
    int parent;
    map<char, int> to;
    string str;

    node(int parent, string &str) {
        this->parent = parent;
        this->str = str;
    }
};

vector<node> trie;

void init() {
    trie.push_back(node(-1, string("")));
}

void split(int n, int pos) {
    trie.push_back(node(trie[n].parent, trie[n].str.substr(0, pos)));
    trie[trie[n].parent].to[trie[n].str[0]] = trie.size() - 1;
    trie[trie.size() - 1].to[trie[n].str[pos]] = n;
    trie[n].str = trie[n].str.substr(pos);
}

void add(string &str) {
    int curnode = 0;
    int curpos = 0;
    for (int i = 0; i < str.length(); i++) {
        if (curpos < trie[curnode].str.length()) {
            if (trie[curnode].str[curpos] == str[i]) {
                curpos++;
                continue;
            } else {
                split(curnode, curpos);
                curnode = trie.size() - 1;
            }
        }
        if (trie[curnode].to.count(str[i]) == 0) {
            trie.push_back(node(curnode, str.substr(i)));
            trie[curnode].to[str[i]] = trie.size() - 1;
        }
        curnode = trie[curnode].to[str[i]];
        curpos = 1;
    }
    if (curpos < trie[curnode].str.length()) {
        split(curnode, curpos);
        curnode = trie.size() - 1;
    }
    if (trie[curnode].to.count('$') == 0) {
        trie[curnode].to['$'] = -1;
    }
}

bool contains(string &str) {
    int curnode = 0;
    int curpos = 0;
    for (int i = 0; i < str.length(); i++) {
        if (curpos < trie[curnode].str.length()) {
            if (trie[curnode].str[curpos] == str[i]) {
                curpos++;
                continue;
            } else {
                return false;
            }
        }
        if (trie[curnode].to.count(str[i]) == 0) {
            return false;
        }
        curnode = trie[curnode].to[str[i]];
        curpos = 1;
    }
    if (curpos < trie[curnode].str.length()) {
        return false;
    }
    if (trie[curnode].to.count('$') == 0) {
        return false;
    }
    return true;
}

int main() {
    init();
    while (true) {
        string command;
        cin >> command;
        if (command == "exit") {
            break;
        } else if (command == "+") {
            string str;
            cin >> str;
            add(str);
        } else if (command == "?") {
            string str;
            cin >> str;
            cout << (contains(str) ? "YES" : "NO") << endl;
        }
    }
}