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
#include<iostream>
using namespace std;
int main(){
	const int MAX=46;
	long long f[MAX]={1,1};
	for(int i=2;i<MAX;i++)f[i]=f[i-1]+f[i-2];
	int n;
	cin>>n;
	cout<<f[n]<<endl;
	return 0;
}
