Instructions: Write the right answer to the question based on the context passage.
Input: Patch's mother was named Silver, because high summer sun made her fur shine that colour. She had a marvellous drey high up a spruce tree, carved out long ago by a woodpecker, and since extended into a two-chambered home full of bright things. The journey along the sky-road to her drey did not take long. When Patch looked inside, he saw a hundred colours glittering in the sunlight, shining from bits of metal and glass set into Silver's walls and floor. But his mother was not there.
He could tell by the faintness of her smell that no squirrel had been here in some time. There were two faint traces of scent, several days old; that of Silver, and that of another squirrel, a musky scent that Patch did not recognize. A scent that made his tail stiffen as if danger was near.
Patch stared into his mother's empty drey for a moment. It wasn't normal for a squirrel to abandon her drey for days, not in the middle of winter. And he hadn't seen Silver for three days. Not since all the acorns had disappeared from the earth.
Patch ran back to his own tree, and then to the maple tree next door, to his brother Tuft's drey. He ran very fast. He was hungrier than ever, and he was beginning to be very worried. He was relieved when he looked into Tuft's drey and found it occupied. Tuft himself was not present, but Brighteyes was, and their babies, and it was clear from the smells that Tuft had only just departed.
"Hello, Patch," Brighteyes said weakly. "Would you like to come in?"
Patch entered. Brighteyes was curled up with her babies in the drey's deepest, warmest corner. The last time Patch had visited, a week ago, this had been a den of noise and chaos, with all Brighteyes' four babies running and jumping and playfighting. Today they lay weakly beside Brighteyes, and the once-shining eyes from which their mother had taken her name were dim and clouded. Question: Who hadn't Patch seen in three days?
Output:
Silver.