Knights and Knaves argue with each other
You're a visitor on the island of Soldons, where there are only two kinds of people: Knights and Knaves. Knights always tell the truth and Knaves always lie. You are walking along a path when a group of four people approach. You ask one of them how many knights are there in the group. Instead, one of them mutters something,and another says: "He said he's a Knave." A third person says to the second person, "You're lying! He must have said he's a knight." The fourth person said to the third person,"Right you are."
So, can you work out how many knights can there be in the group?