Given an integer n, calculate the nth Fibonacci number using recursion. The Fibonacci sequence starts with 0 and 1: F(0) = 0, F(1) = 1, and F(n) = F(n-1) + F(n-2) for n > 1.
Explanation: F(3) = F(2) + F(1) = 1 + 1 = 2.