Read the following passage to answer the question

One day, the Giant came back. He had been to visit his friend, the Cornish ogre, and had stayed with him for seven years. After the seven years were over, he had said all that he had to say, for his conversation was limited, and he was determined to return to his own castle. When he arrived, he saw the children playing in the garden.

"What are you doing here?" he cried in a very gruff voice, and the children ran away.

"My own garden is my own garden," said the Giant; "anyone can understand that, and I will allow nobody to play in it but myself." So he built a high wall all round it, and put up a notice-board.

TRESPASSERS WILL BE PROSECUTED

He was a very selfish Giant.

Adapted from American Literature

3. How did the giant warn the children?