Background

As everyone knows, the loftiest goal of an OIer is to get AK at IOI.

(Image from “From Beginner to Pro: Programming Contest Basics”.)

As an OIer, Little Z also wants to AK IOI. But he is still too weak: even saying I AK IOI would make the top players look down on him.

So, Little Z can only say |A|<|O| to encourage himself.

However, the expert Youyou saw it and felt it was ridiculous, saying: With your level you still want to AK IOI? Fine, since you said |A|<|O|, I will give you a problem to do.

Poor Little Z is really too weak and cannot solve even this problem, so he has to ask you for help—the future IOI AKer.

Problem Description

Given $O$, find the number of integers $A$ such that $|A|<O$.

Since Little Z is too weak, he does not even dare to say |A|<|O|, and can only study the problem |A|<O.

Input Format

One line with one integer $O$.

Output Format

One line with one integer: the number of integers $A$ that satisfy the condition.

3

5

1145141919810

2290283839619

12345

24689

Hint

Sample 1 Explanation

Possible values of $A$ are $-1$, $0$, and $1$.

Constraints

• Subtask 1 (30 points): $0 \le |O| \le 2^{10}-1$;
• Subtask 2 (60 points): $0 \le |O| \le 2^{31}-1$;
• Subtask 3 (10 points): $0 \le |O| \le 2^{63}-1$.

$|O|$ denotes the absolute value of $O$.

Hint

If you do not know what absolute value is, you can understand it as:

$$|x| = \begin{cases} x & (x > 0) \\ 0 & (x = 0) \\ -x & (x < 0)\end{cases}$$

Original idea: Meatherm

Translated by ChatGPT 5