من طرف A man and his dog
A man and his dog live at the bottom of a hill. It is their habit every morning to walk the three miles to the top of the hill and then back. Well, time has gone on and the dog has gotten older. The man still walks to the top of the hill every morning, but the dog has gotten older and can't quite keep up with him.
What they now do is this: The man starts out at his usual steady pace and his dog follows but at half his owner's speed. So when the man reaches the top he turns around and starts back down, maintaining the same steady pace. Before long he meets the dog coming up the hill and at this point the dog turns around and starts back down again.
Because they're going down the hill, now the man and the dog walk at the same speed down the hill because the dog doesn't have a hard time keeping up going downhill.
How far does his dog walk???????????
What they now do is this: The man starts out at his usual steady pace and his dog follows but at half his owner's speed. So when the man reaches the top he turns around and starts back down, maintaining the same steady pace. Before long he meets the dog coming up the hill and at this point the dog turns around and starts back down again.
Because they're going down the hill, now the man and the dog walk at the same speed down the hill because the dog doesn't have a hard time keeping up going downhill.
How far does his dog walk???????????
Well, if it did happen to me one day, then i will just try all the switches randomly till i get them all on 
