#include <iostream>
using namespace std;

int main(){
  int m=1,u=1,n,h;
  cin>>n;
  for(int i=2;i<=n;i++){
    h=u;
    u+=m;
    m=h;
  }
  cout<<u<<endl;
  return 0;
}
### Prompt

Please formulate 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 m=1,u=1,n,h;
  cin>>n;
  for(int i=2;i<=n;i++){
    h=u;
    u+=m;
    m=h;
  }
  cout<<u<<endl;
  return 0;
}
```