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 Python3 (judge verdict: Accepted)

def main():
    import sys
    input=sys.stdin.readline

    n=int(input())
    if n==0 or n==1:
      print(1)
      return 
      
    dp=[0]*(1+n)
    dp[0]=1
    dp[1]=1
    for i in range(n-1):
        dp[i+2]=dp[i+1]+dp[i]
    
    print(dp[-1])   
 
if __name__=='__main__':
    main()