Please solve the programming task below using a self-contained code snippet in a markdown code block.

The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. That is,

F(0) = 0, F(1) = 1
F(n) = F(n - 1) + F(n - 2), for n > 1.

Given n, calculate F(n).
 
Please complete the following python code precisely:
```python
class Solution:
    def fib(self, n: int) -> int:
```