Counting Integers with |A| < O

Given an integer O, count the number of integers A (where A is an integer) that satisfy the inequality \(|A| < O\). Note that if O is non-positive, there will be no such integers.

For instance, when O = 5 the integers satisfying this condition are: -4, -3, -2, -1, 0, 1, 2, 3, 4, totaling 9 numbers.

Note: The inequality is \(|A| < O\) rather than \(|A| < |O|\) — the condition is directly on O.

inputFormat

The input consists of a single integer O.

Input Format:

O

outputFormat

Output a single integer, which is the count of integers A satisfying \(|A| < O\).

Output Format:

result

sample

0

0