Assistant Xin discovers the truth

The sun shone brightly in the sky and with that, the big day finally arrived, but poor Assistant Xin was busy collecting all the papers from the official archives that Jinhai signed around the time Grandma Liu was hospitalized.

"Alright, I guess that's it.", and he placed the stack of files on his desk.

He sat down and meticulously started checking each and every one of them. But, even after twenty minutes, he didn't find anything suspicious. Those were all the usual confidential documents of the deals that Liu Corps was involved at that time.

Strange. There is nothing wrong with any of these papers. So, what does the fourth letter mean?

Then his sight went onto his computer where he had the record of how many documents Jinhai had signed that day. He has a habit. He always makes an official note of the total count of only those very important and confidential documents that Jinhai signs sometimes.

Wherever sensitive information is involved, Assistant Xin is always extra careful.