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#				 Author: Udit "luctivud" Gupta @ https://www.linkedin.com/in/udit-gupta-1b7863135/					 #


import math;   		from collections import *
import sys;   		from functools import reduce
import time;   		from itertools import groupby

# sys.setrecursionlimit(10**6)

def input()         : return sys.stdin.readline()
def get_ints()      : return map(int, input().strip().split())
def get_list()      : return list(get_ints())
def get_string()    : return list(input().strip().split())
def printxsp(*args) : return print(*args, end="")
def printsp(*args)  : return print(*args, end=" ")


DIRECTIONS = [(+0, +1), (+0, -1), (+1, +0), (+1, -1)] 
NEIGHBOURS = [(-1, -1), (-1, +0), (-1, +1), (+0, -1),\
              (+1, +1), (+1, +0), (+1, -1), (+0, +1)]



# MAIN >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

# for _test_ in range(int(input())): 

x, k, d = get_ints()
x = abs(x)
el_facto = min(k, (x + d-1) // d)
moves = []
if k & 1:
	if el_facto & 1:
		moves.append(el_facto)
		el_facto -= 2
		if (el_facto > 0 and el_facto <= k) :
			moves.append(el_facto)
		if el_facto + 4 <= k:
			moves.append(el_facto + 4)
	else:
		el_facto -= 1
		moves.append(el_facto)
		el_facto -= 2
		if (el_facto > 0 and el_facto <= k) :
			moves.append(el_facto)
		if el_facto + 4 <= k:
			moves.append(el_facto + 4)
else:
	if not (el_facto & 1):
		moves.append(el_facto)
		el_facto -= 2
		if (el_facto > 0 and el_facto <= k) :
			moves.append(el_facto)
		if el_facto + 4 <= k:
			moves.append(el_facto + 4)
	else:
		el_facto -= 1
		moves.append(el_facto)
		el_facto -= 2
		if (el_facto > 0 and el_facto <= k) :
			moves.append(el_facto)
		if el_facto + 4 <= k:
			moves.append(el_facto + 4)
ans = float('inf')
x = abs(x)
# print(moves)
for i in moves:
	ans = min(ans, abs(x - i * d))
print(ans)




Measured memory_bytes: 67800