Problem Statement

Takahashi, who lives on the number line, is now at coordinate X. He will make exactly K moves of distance D in the positive or negative direction.
More specifically, in one move, he can go from coordinate x to x + D or x - D.
He wants to make K moves so that the absolute value of the coordinate of the destination will be the smallest possible.
Find the minimum possible absolute value of the coordinate of the destination.

Input

Input is given from Standard Input in the following format:
X K D

Output

Print the minimum possible absolute value of the coordinate of the destination.

Constraints

• -$10^{15} \leq X \leq 10^{15}$
• $1 \leq K \leq 10^{15}$
• 1 $\leq D \leq 10^{15}$
• All values in input are integers.

Sample Input 1

6 2 4

Sample Output 1

2

Takahashi is now at coordinate 6. It is optimal to make the following moves:

• Move from coordinate 6 to (6 - 4 =) 2.
• Move from coordinate 2 to (2 - 4 =) -2.

Here, the absolute value of the coordinate of the destination is 2, and we cannot make it smaller.

Sample Input 2

7 4 3

Sample Output 2

1

Takahashi is now at coordinate 7. It is optimal to make, for example, the following moves:

• Move from coordinate 7 to 4.
• Move from coordinate 4 to 7.
• Move from coordinate 7 to 4.
• Move from coordinate 4 to 1.

Here, the absolute value of the coordinate of the destination is 1, and we cannot make it smaller.

Sample Input 3

10 1 2

Sample Output 3

8

Sample Input 4

1000000000000000 1000000000000000 1000000000000000

Sample Output 4

1000000000000000

The answer can be enormous.

见题面 Input 部分

见题面 Output 部分