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.

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.

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.

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

见题面 Input 部分

见题面 Output 部分