#include <iostream>
using namespace std;

int main () {
	int n;
	cin >> n;
	int F[50];
	F[0] = F[1] = 1;
	for (int i=2; i<=n; ++i) F[i] = F[i-1] + F[i-2];
	cout << F[n] << endl;
	return 0;
}



### Prompt

Your challenge is to write a CPP solution to the following problem:

Write a program which prints $n$-th fibonacci number for a given integer $n$. The $n$-th fibonacci number is defined by the following recursive formula:

\begin{equation*} fib(n)= \left \\{ \begin{array}{ll} 1 & (n = 0) \\\ 1 & (n = 1) \\\ fib(n - 1) + fib(n - 2) & \\\ \end{array} \right. \end{equation*}

Constraints

* $0 \leq n \leq 44$

Input

An integer $n$ is given.

Example

Input

3


Output

3

### Response

```cpp
#include <iostream>
using namespace std;

int main () {
	int n;
	cin >> n;
	int F[50];
	F[0] = F[1] = 1;
	for (int i=2; i<=n; ++i) F[i] = F[i-1] + F[i-2];
	cout << F[n] << endl;
	return 0;
}



```