Peaches Eaten Day by Day (Find the Initial Count)

Problem Description

On the first day a monkey picked some peaches. He ate half of them right away, but that was not enough, so he ate one more. The next morning he ate half of the remaining peaches, plus one more. Every following morning he ate half of the previous day's remainder plus one more. On the $N$-th morning, when he wanted to eat again, only one peach was left. How many peaches did he pick on the first day?

Input Format

The input gives a positive integer $N$ ($1 < N \le 10$) on one line.

Output Format

Output on one line the number of peaches picked on the first day.

Sample Input

3

Sample Output

10

Constraints

$1 < N \le 10$