#include<iostream>
using namespace std;
int main(void){
int n;
int a=1,b=1,tmp=1;

cin>>n;

for(int i=2; i<n+1; i++){
  tmp = a + b;
  a = b;
  b = tmp;
}

cout<<tmp<<endl;

return 0;
}





### Prompt

Your task is to create 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(void){
int n;
int a=1,b=1,tmp=1;

cin>>n;

for(int i=2; i<n+1; i++){
  tmp = a + b;
  a = b;
  b = tmp;
}

cout<<tmp<<endl;

return 0;
}





```