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: Time Limit Exceeded)

#include <stdio.h>

int fibonatti( int );
int main()
{
  int n, fibn;
  
  scanf("%d", &n);

  fibn = fibonatti( n );
  printf("%d\n", fibn);
  
  return 0;
}

int fibonatti(int n)
{
  int F[100];
  F[n] = 0;
  if(n == 0 || n == 1)
    {
      F[n] = 1;
      return F[n];
    }
  if(F[n] != 0) return F[n];
  else
    {
      F[n] = fibonatti(n-2) + fibonatti(n-1);
      return F[n];
    }
}