Nenokku (Easy)#5289
A very famous author of a no less famous book decided to write a sequel to his work. He wrote all his books on a computer connected to the Internet. Due to this carelessness, a boy named Nenokku managed to gain access to the unfinished book. Every evening, the boy would sneak onto the writer's computer and copy the new passages to his own computer. After copying another chapter, Nenokku wondered whether the writer had ever used the word "book". However, since he prefers browsing the Internet to reading books, he asks you to find out whether certain words appear in the text. Naturally, he is interested in more than just one word.
Each line of the input file contains one of two types of entries:
? <word> (word is a string of up to Latin letters);
A <text> (text is a string of up to 10^5 Latin letters).
An entry starting with ? requests to check whether the substring word exists in the main text (case-insensitive).
An entry starting with A requests to append the string text to the main text.
The writer has only just begun working on his masterpiece, so he could not have written more than characters so far. The total size of the input file does not exceed kilobyte.
For each line of type ?, output "YES" if the substring word exists in the main text, and "NO" otherwise. The search should be case-insensitive.
Example 1