Midterm Question 2 (20%) - 2nd

Question

    Suppose there is a pair of newborn bunnies in the pasture in the first month, each pair of male and female bunnies grew into a large male and female rabbits after two months later. After three months from the start, each pair of male and female rabbit can give birth to a pair of small bunnies every month. If the rabbits can live forever, how many pairs of rabbits in the pasture in the first N month?

(1<=N<=90)(Very IMPORTANT)

Input

3

Output

2

 

Input

5

Output

5

 

Input

88

Output

1100087778366101931

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