Your task this time will be on computing Fibonacci numbers. Sounds easy!... or is it?

The Fibonacci numbers are a sequence of numbers generated by taking the sum of the preceding two values. Formally, the sequence is defined as:

$${\displaystyle f(n)=\{\begin{array}{ll}1& \text{if }n=1\\ 1& \text{if }n=2\\ f(n-1)+f(n-2)& \text{if }n\ge 3\end{array}}$$

Given an integer $n$ $(1\le n\le 50)$, you are to output the $n^{\text{th}}$ Fibonacci number.

Note: You may only submit to this problem in Python 3.

Input Specification

The first line of input contains a single integer $n$.

Output Specification

Output on a single line, the $n^{\text{th}}$ Fibonacci number.

Scoring

Your score will be computed based on the length of your source code, the shorter the better. For an $L$-byte program,

• if $L\le 43$, you will receive the full $100$ points.
• if $44\le L\le 47$, you will receive $80-10\times (L-44)$ points.
• if $48\le L$, you will receive $\lfloor 2^{0.16(80-L)}\rfloor$ points.

Sample Input

8

Sample Output

21