A c-tree is a tree with each node colored either red, green or silver that obeys the following rules: Each red node has two children, exactly one of which is green. Each green node has exactly one child, which is not green Silver nodes have no children. Let R and S respectively denote the number of red and silver nodes, and n be the total number of nodes. Prove by induction that in any C-tree with n >1, S= R +1