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;

public static class Program
{
  static int[] fib = new int[100];
  
  public static void Main(string[] args)
  {
    int input = int.Parse(Console.ReadLine());
    int output = Fib(input);
    
    Console.WriteLine(output);
  }
  
  public static int Fib(int n)
  {
    if(n == 0) return fib[0] = 1;
    if(n == 1) return fib[1] = 1;
    
    if(fib[n] == 0)
    {
      return fib[n] = Fib(n - 2) + Fib(n - 1);
    } 
    else
    {
      return fib[n];
    }
  }
}