We stand with a friend at the entrance and wait for his girlfriend. The younger sister of the girl (7 years old) comes out and we begin to talk with her... The conversation began about the pieces, well, we naturally do not understand this. On what she says: "We need to add two more to 13... It will be 15... Hm, so soon it will reach 20". We do not understand anything at all and ask what she is about... What she replied: "This is the number of fools I know!"