#include <iostream>

using namespace std;

int main() {
    int n;
    int a=0,b=1;
    int c;
    cin>>n;
    for (int i=0;i<=n;i++) {
        c=a+b;
        a=b;
        b=c;
    }
    cout<<a<<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 a=0,b=1;
    int c;
    cin>>n;
    for (int i=0;i<=n;i++) {
        c=a+b;
        a=b;
        b=c;
    }
    cout<<a<<endl;
}

```