Yi Feng looked at the knot and kept calculating in his head how to untie it. But the more calculation, the more pain Yi Feng felt in his head. A stream of sweat poured out, obviously tired to the extreme.

However, even if Yi Feng used his brain so quickly, he still couldn't find where to start. It's like an unsolved problem.

Yi Feng is not afraid of all the problems of arithmetic, intelligence and so on. But for this kind of problem, even Yi Feng, who has confidence in himself, also feels a great crisis.

looking at the knot in front of him, Yi Feng kept scanning it. After...