Calculate 2 × (\frac{n!}{n!!})

Given an integer \(n\), calculate the value of \(2 \times \frac{n!}{n!!}\).

Note:

• \(n!\) denotes the factorial of \(n\): \(n! = 1 \times 2 \times \cdots \times n\).
• \(n!!\) denotes the double factorial of \(n\), defined as follows:

• If \(n\) is even: \(n!! = n \times (n-2) \times \cdots \times 2\).
• If \(n\) is odd: \(n!! = n \times (n-2) \times \cdots \times 1\).

inputFormat

The input consists of a single integer \(n\).

outputFormat

Output a single integer representing the value of \(2 \times \frac{n!}{n!!}\).

sample

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