import math
X = int(input())
Y = int(input())
L = int(input())

cnt = 0

if X == 0:
	if Y == 0:
		cnt = 0
	elif Y > 0:
		cnt += abs(math.ceil(Y/L))
	else:
		cnt += abs(math.ceil(Y/L)) + 2
elif X > 0:
	if Y == 0:
		cnt += abs(math.ceil(X/L)) + 1
	elif Y > 0:
		cnt += abs(math.ceil(X/L)) + abs(math.ceil(Y/L)) + 1
	else:
		cnt += abs(math.ceil(Y/L)) + abs(math.ceil(Y/L)) + 2
else:
	if Y == 0:
		cnt += abs(math.ceil(X/L)) + 1
	elif Y > 0:
		cnt += abs(math.ceil(X/L)) + abs(math.ceil(Y/L)) + 1
	else:
		cnt += abs(math.ceil(Y/L)) + abs(math.ceil(Y/L)) + 2

print(cnt)