Problem:
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Fibonacci Number

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*}

Input

An integer $n$ is given.

output

Print the $n$-th fibonacci number in a line.

Constraints

$0 \leq n \leq 44$

Sample Input 1

3

Sample Output 1

3

Solution in C# (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    static long FibonacciNumber(long[] a, int n)
    {       
        a[0] = 1;
        a[1] = 1;
        
        for(int i = 2; i <= n; i++)
        {
            a[i] = a[i - 1] + a[i - 2];
        }
        return a[n];
    }

    static void Main(string[] args)
    {
        int n = int.Parse(Console.ReadLine());
        long[] a = new long[n + 1];

        Console.WriteLine(FibonacciNumber(a, n));
    }
}