With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: In South Korea, April 5, Singmogil or Sikmogil (식목일), the Arbor Day, was a public holiday until 2005. Even though Singmogil is viewed as an ordinary day, the day is still celebrated, with the South Korean public continuing to take part in tree-planting activities.
text_B: Do Koreans celebrate only official holidays?
NO.