#include<iostream>
using namespace std;
int main(){
    int i,a;
    int A[50];
    cin>>a;
    A[0]=A[1]=1;
    for(i=2;i<=a;i++) A[i]=A[i-1]+A[i-2];
    cout<<A[a]<<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 i,a;
    int A[50];
    cin>>a;
    A[0]=A[1]=1;
    for(i=2;i<=a;i++) A[i]=A[i-1]+A[i-2];
    cout<<A[a]<<endl;
    return 0;
}

```