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 F(int f){
  if(f< 2)return 1;
  return F(f-1)+F(f-2);
}

/*
int F(int n){
  int f[3]={1,1,1};
  while(1<n--){
    f[2]=f[0]+f[1];
    f[0]=f[1];
    f[1]=f[2];
  }
  return f[2];
}
*/
int main(){
  int n;
  scanf("%d",&n);
  printf("%d\n",F(n));
  return 0;
}