# Problem 340: Crazy Function
For fixed integers a, b, c, define the crazy function F(n) as follows:
F(n) = n - c for all n > b F(n) = F(a + F(a + F(a + F(a + n)))) for
all n ≤ b. Also, define S(a, b, c) = . For example, if a = 50, b = 2000
and c = 40, then F(0) = 3240 and F(2000) = 2040. Also, S(50, 2000, 40) =
5204240. Find the last 9 digits of S(217, 721, 127).