#include<bits/stdc++.h>
using namespace std;
int main()
{
	char c;
	string s="",s1;

	freopen("nenokku_easy.in", "r", stdin);
    freopen("nenokku_easy.out", "w", stdout);
     while(cin >> c >>s1)
    {
		transform(s1.begin(), s1.end(), s1.begin(), ::tolower);
		if(c=='?')
		{
			if(s.find(s1) != -1)
				cout<<"YES";
			else
				cout<<"NO";
		}
		else if(c=='A')
		{
			s+=s1;
		}
	}
	fclose(std)
}