Problem:
Score : 300 points

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.

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.

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.

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.

Solution in C# (.NET Core 3.1.201) (judge verdict: Runtime Error)

using System;
using System.Collections.Generic;

namespace atcoder
{
    class Program
    {
        static void Main(string[] args)
        {
            //X = kordinat 2D                                   Input form = X, K, D
            //K = Antalet rörelser                                 Målet är att komma så nära 0 som möjligt
            //D = Distans för varje rörelse             Så en Move blir X2  = X1 +- (D * K)

            string[] input = Console.ReadLine().Split(' ');
            int X = int.Parse(input[0]);
            int K = int.Parse(input[1]);
            int D = int.Parse(input[2]);
            for (int i = 0; i < K; i++)
            {
                int nextValPos = Math.Abs(X + D);
                int nextValNeg = Math.Abs(X - D);

                if (nextValPos >= nextValNeg)
                    X = X - D;
                else if (nextValPos < nextValNeg)
                    X = X + D;
            }

            Console.WriteLine(X);
        }
    }
}