Zero

The moment breakfast was over, Qing Chen was out of his seat and was following Master to his office. He was about three paces behind and he took smaller steps. When Master walked, it was as if he had all the time in the world. But the slow pace did not help calm Qing Chen's raging heart.

He knows. There's no way that he does not know, Qing Chen thought. It would be impossible to not get caught with the stunt they pulled last night. They must have left something out of place. Or did not replace an object in its EXACT location.

There were a thousand ways they could've left evidences in that room last night. Did they lock the door? Wuming was last one out so he probably did, he wouldn't be able to make a small mistake like th—

"In you go," said Master and held the door open for Qing Chen.