Special Summation Sequence

You are given a sequence defined as follows:

• \(a_1 = 1\) and \(a_2 = 2\)
• For \(n > 2\), \(a_n = a_1 + a_2 + \cdots + a_{n-1}\).

Your task is to compute the \(n\)th term of this sequence.

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Examples:

Input: 3
Output: 3
Input: 5
Output: 12
Input: 7
Output: 48

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Note: Use precise arithmetic as the sequence may grow quickly.

inputFormat

The input consists of a single line containing one integer \(n\) (\(n \geq 1\)), representing the position in the sequence you are required to compute.

outputFormat

Output a single integer: the value of the \(n\)th term in the sequence.

## sample

1

1