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 n;
int F[1000];

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

int main(){
  int i;

  for(i=0; i<1000; i++){
    F[i] = -1;
  }

  scanf("%d",&n);

  printf("%d\n",fibonacci(n));

  return 0;
}