Problem Statement

Takahashi is at the origin of a number line. He wants to reach a goal at coordinate $X$.

There is a wall at coordinate $Y$, which Takahashi cannot go beyond at first.
However, after picking up a hammer at coordinate $Z$, he can destroy that wall and pass through.

Determine whether Takahashi can reach the goal. If he can, find the minimum total distance he needs to travel to do so.

Constraints

• $\-1000 \\leq X,Y,Z \\leq 1000$
• $X$, $Y$, and $Z$ are distinct, and none of them is $0$.
• All values in the input are integers.

Input

The input is given from Standard Input in the following format:

$X$ $Y$ $Z$

Output

If Takahashi can reach the goal, print the minimum total distance he needs to travel to do so. If he cannot, print -1 instead.

Sample Input 1

10 -10 1

Sample Output 1

10

Takahashi can go straight to the goal.

Sample Input 2

20 10 -10

Sample Output 2

40

The goal is beyond the wall. He can get there by first picking up the hammer and then destroying the wall.

Sample Input 3

100 1 1000

Sample Output 3

-1