Brain Teaser or Math Problem?

One day at noontime six children became lost in a cave. Fortunately they had just enough food to feed themselves for four days. Unfortunately, at noon on the next day they met another group of lost children who had no food but with whom they shared their rations equally. Fortunately, they all had just enough food to last them until they were all rescued at noon two days after their groups joined. How many children were in that second group? .