In either Java or C#

Instead of a regular Fibonacci number, you are supposed to calculate a special one as follows:

F(n) = F(n-1)+ 2 * F(n-2) + 3 * F(n-3)

As an example, if F(0) = F(1) = F(2) = 1, then we have:

F(3) = F(2) + 2 * F(1) + 3 * F(0) = 1 + 2 + 3 = 6 F(4) = F(3) + 2 * F(2) + 3 * F(1) = 6 + 2 + 3 = 11

Given F(0), F(1), F(2), and N, your job is to calculate F(N).

Input Format

First number is F(0), second number is F(1), third number is F(2), and last number is N.

Example input: 1 1 1 4