Yu Jiayuan led Fang Heng to a corner of the bar and explained in a low voice, "When the pollution reaches a certain level, one will sometimes receive a summoning from the pollution source. You can ignore or follow the summoning to assemble."
Fang Heng was stunned when he heard that and instantly became alert, "Wait, according to what you said, we have already found your pollution source?"
"That's not it. Pollution can be divided into direct and indirect pollution. For example, pollution source A polluted B, and B, as an indirect Polluted, polluted C. If we were C, we could only completely remove the pollution by eliminating source A. After B falls, it can summon C, D, E, F, and all the lower chains below it."
Fang Heng rubbed his chin and realized the trouble of pollution.
They had to find their pollution source by tracking them down individually.
