easyRecursion
Fibonacci Number
## Problem
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)`.
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)`.
Examples
Input
n = 2
Output
1
F(2) = F(1) + F(0) = 1 + 0 = 1.
Input
n = 3
Output
2
F(3) = F(2) + F(1) = 1 + 1 = 2.
Input
n = 4
Output
3
F(4) = F(3) + F(2) = 2 + 1 = 3.
Constraints
0 <= n <= 30
Python
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