Oneday, there were three person who ride on the train in the Ireland. They ware mathematician, astronomer and physicist. When astronomer looked out of the window of the train, he found a black sheep.Astronomer said, "This is interesting! Any sheep is black that there are in the Ireland." At that time, pyisicist responsed, "You are mistaken. That means one out of the all sheep is black." At that time, mathematician responsed, "you are mistaken. One out of the all sheep is black and one side of the sleep is black."
Do you know this tales? When I was high school student, I was impressed in this.
How about you?
