#include<iostream>
using namespace std;
int main(){
  int f[3]={1,1,1},n;
  cin >> n;
  while(1<n--){
    f[2]=f[0]+f[1];
    f[0]=f[1];    
    f[1]=f[2];
  }
  cout<<f[2]<<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>
using namespace std;
int main(){
  int f[3]={1,1,1},n;
  cin >> n;
  while(1<n--){
    f[2]=f[0]+f[1];
    f[0]=f[1];    
    f[1]=f[2];
  }
  cout<<f[2]<<endl;
  return 0;
}
```