#![allow(unused_parens)]
#![allow(unused_imports)]
#![allow(non_upper_case_globals)]
#![allow(non_snake_case)]
#![allow(unused_mut)]
#![allow(unused_variables)]
#![allow(dead_code)]

use itertools::Itertools;
use proconio::input;
use proconio::marker::{Chars, Usize1};

#[allow(unused_macros)]
#[cfg(debug_assertions)]
macro_rules! mydbg {
    //($arg:expr) => (dbg!($arg))
    //($arg:expr) => (println!("{:?}",$arg));
      ($($a:expr),*) => {
          eprintln!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
      }
}
#[cfg(not(debug_assertions))]
macro_rules! mydbg {
    ($($arg:expr),*) => {};
}

macro_rules! echo {
    ($($a:expr),*) => {
          $(println!("{}",$a))*
      }
}

use std::cmp::*;
use std::collections::*;
use std::ops::{Add, Div, Mul, Sub};

#[allow(dead_code)]
static INF_I64: i64 = 92233720368547758;
#[allow(dead_code)]
static INF_I32: i32 = 21474836;
#[allow(dead_code)]
static INF_USIZE: usize = 18446744073709551;
#[allow(dead_code)]
static M_O_D: usize = 1000000007;
#[allow(dead_code)]
static PAI: f64 = 3.1415926535897932;

trait IteratorExt: Iterator {
    fn toVec(self) -> Vec<Self::Item>;
}

impl<T: Iterator> IteratorExt for T {
    fn toVec(self) -> Vec<Self::Item> {
        self.collect()
    }
}

trait CharExt {
    fn toNum(&self) -> usize;
    fn toAlphabetIndex(&self) -> usize;
    fn toNumIndex(&self) -> usize;
}
impl CharExt for char {
    fn toNum(&self) -> usize {
        return *self as usize;
    }
    fn toAlphabetIndex(&self) -> usize {
        return self.toNum() - 'a' as usize;
    }
    fn toNumIndex(&self) -> usize {
        return self.toNum() - '0' as usize;
    }
}

trait VectorExt {
    fn joinToString(&self, s: &str) -> String;
}
impl<T: ToString> VectorExt for Vec<T> {
    fn joinToString(&self, s: &str) -> String {
        return self
            .iter()
            .map(|x| x.to_string())
            .collect::<Vec<_>>()
            .join(s);
    }
}

trait StringExt {
    fn get_reverse(&self) -> String;
}
impl StringExt for String {
    fn get_reverse(&self) -> String {
        self.chars().rev().collect::<String>()
    }
}

trait UsizeExt {
    fn pow(&self, n: usize) -> usize;
}
impl UsizeExt for usize {
    fn pow(&self, n: usize) -> usize {
        return ((*self as u64).pow(n as u32)) as usize;
    }
}

fn main() {
    input! {
       X: i64,
       K:i64,
       D:i64,
    }

    let mut ans: usize = 0;
    let a = X.abs() / D;
    let b = (X.abs() + D - 1) / D;
    let c = (X.abs() - (D * a).abs()).abs();
    let d = (X.abs() - (D * b).abs()).abs();
    mydbg!(a, b, c, d);
    if (a <= K && a % 2 == K % 2) && (b <= K && b % 2 == K % 2) {
        echo!(min(c, d));
    } else if a <= K && a % 2 == K % 2 {
        echo!(c);
    } else if b <= K && b % 2 == K % 2 {
        echo!(d);
    } else if a <= K && b <= K {
        let mut e = INF_I64;
        e = (X.abs() - (D * (b + 1)).abs()).abs();
        if b >= 1 {
            e = min(e, (X.abs() - (D * (b - 1)).abs()).abs());
        }
        e = min(e, (X.abs() - (D * (a + 1)).abs()).abs());
        if a >= 1 {
            e = min(e, (X.abs() - (D * (a - 1)).abs()).abs());
        }
        echo!(e);
    } else if a <= K {
        let mut e = INF_I64;
        e = min(e, (X.abs() - (D * (a + 1)).abs()).abs());
        if a >= 1 {
            e = min(e, (X.abs() - (D * (a - 1)).abs()).abs());
        }
        echo!(e);
    } else if b <= K {
        let mut e = INF_I64;
        e = (X.abs() - (D * (b + 1)).abs()).abs();
        if b >= 1 {
            e = min(e, (X.abs() - (D * (b - 1)).abs()).abs());
        }
        echo!(e);
    } else {
        echo!((X.abs() - (D * K).abs()).abs());
    }
}


Measured memory_bytes: 2152