#include<iostream>
#include <string>
using namespace std;
int a,ans[46];
int main(){
	cin>>a;
	ans[0]=1,ans[1]=2;
	for(int i=0;i<a;i++){
	ans[i+2]=ans[i+1]+ans[i];}
	cout<<ans[a-1]<<endl;
		    return 0;
	}

### Prompt

Construct a Cpp code solution to the problem outlined:

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>
#include <string>
using namespace std;
int a,ans[46];
int main(){
	cin>>a;
	ans[0]=1,ans[1]=2;
	for(int i=0;i<a;i++){
	ans[i+2]=ans[i+1]+ans[i];}
	cout<<ans[a-1]<<endl;
		    return 0;
	}

```