Fibonacci Number

Given an integer n, compute the n^th Fibonacci number. The Fibonacci sequence is defined as follows:

$$F_0 = 0, \quad F_1 = 1, \quad \text{and} \quad F_n = F_{n-1} + F_{n-2} \text{ for } n \geq 2.$$

Your task is to read an integer from standard input and output the corresponding Fibonacci number.

inputFormat

The input consists of a single integer n (with 0 ≤ n ≤ 90) representing the index in the Fibonacci sequence.

outputFormat

Output a single number which is the n^th Fibonacci number.

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