Once there were two brothers, Peter and Bernard. Both of them liked to ride horses. One day they both went to buy a horse. Bernard bought a horse and Peter bought a horse, too.
"Oh, dear!" said Bernard. "How are we going to tell our horses apart? How shall I know which is my horse and which is your horse?"
"It isn't difficult," said Peter, "you cut the tail of your horse shorter than that of mine."
So Bernard cut the tail of his horse and now they could see which horse was his. But then the tail of Bernard's horse grew and the brothers began to think again.
"I know!" said Bernard. "You cut the mane of your horse very short and so we'll see which horse is yours."
But soon the mane of his horse grew.
"Do you know what we must do?" asked Peter. "We must see whose horse is longer. Perhaps, one is longer than the other."
And at last they found that the black horse was three centimetres longer than the white horse.