What was The Song of the Winter Solstice in the book, Escape from Camp 14?

When Shin was training Park in the garment factory, he was annoyed by Park’s constant singing. Finally, Shin gave in and learned the lyrics to the song, “Song of the Winter Solstice” which recent defectors had learned as the theme song of a popular TV series. It was a fitting song because it spoke of companions who had to endure hard times and pain. It was the only song Shin knew at the time. It is the only one he sings now.