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>
#define N 44
int fibonach(int );

int main()
{
  int fn,n;

  scanf("%d",&n);

  fn = fibonach(n);

  printf("%d\n",fn);
  
  return 0;
}


int fibonach(int n)
{
  int f,i,a[N];

  a[0] = 1;
  a[1] = 1;

  if(n == 0 || n == 1) return 1;
  
  f = fibonach(n - 1) + fibonach(n - 2);

  return f;
  
}