City Festival#637

City Festival

1 second

64 megabytes

Very easy

The city of Luminara is preparing for its annual Festival of Lights. The main square has been divided into an $N \times N$ N \times N grid of sections for decoration.

The festival organizers have devised a special decoration pattern: the first section will have $1$ lantern, the second section will have $2$ lanterns, the third will have $4$ lanterns, and so on. Each subsequent section receives twice as many lanterns as the previous one.

The city council needs to know the total number of lanterns that must be ordered for the entire square.

Help the festival organizers calculate how many lanterns are needed in total.

Input

A single number — the size of the square grid $N$ ( $1 \leq N \leq 100$ 1 \leq N \leq 100).

Output

A single number — the total number of lanterns required.

Examples

Example 1

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N \times N

1 \leq N \leq 100