IBM interview questions (about 50 dogs, 50 people, sick dogs)

Question: there are 50 people in the village, each having a dog. Among the 50 dogs, there are sick dogs (this disease is not contagious), so people need to find the sick dogs.

Everyone can observe the other 49 dogs to determine whether they are ill (if they are ill, they can be seen). Only their dogs can be seen, and the observed results cannot be exchanged, the owner of the sick dog cannot be notified. Once the host determines that the dog in his house is a sick dog, the dog is shot at himself (the dog must be shot within one day after discovery), and each person only has the right to shoot his dog, there is no right to kill other dogs.

On the first day, we all finished reading it, but the gun didn't sound. On the third day, there was a gunshot and asked how many sick dogs were found in the village.