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 Kotlin (1.3.71) (judge verdict: Accepted)

fun main() {
    // 文字列
//    var n = readLine()!!.toInt()
//    val x: String = readLine()!!
    // 数値
//    val int =readLine()!!.toInt()
    // 行
//    val list = readLine()!!.split(" ").map (String::toInt )
    var (x, k, d) = readLine()!!.split(" ").map(String::toLong)
//    val xys = List(n) {
////        readLine()!!.split(" ").map(String::toLong)
//        readLine()!!.toDouble()
//    }
    
    x=Math.abs(x)
    var ans=0L
    if (x / d >= k) {
        ans=x - k * d
    } else {
        val street_step = (x / d).toLong()
        val remainder_step = k - street_step
        if (remainder_step % 2 == 0L) {
            ans=x-(street_step*d)
        }else{
            ans=Math.abs(x-(street_step*d)-d)
        }
    }
    print(ans)

}