#include<iostream>

using namespace std;

int main(){

  int n;

  int n1,n2,st;
  n1=1;
  n2=1;
  st=1;

  cin >>n;

  for(int i=1;i<n;i++){
    st=n1+n2;
    n1=n2;
    n2=st;
  }
  cout <<st<<endl;

}
### 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 n;

  int n1,n2,st;
  n1=1;
  n2=1;
  st=1;

  cin >>n;

  for(int i=1;i<n;i++){
    st=n1+n2;
    n1=n2;
    n2=st;
  }
  cout <<st<<endl;

}
```